AC4490
User Guide
Version 4.5
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Hong Kong: +852-2923-0610
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AC4490 User Guide
Version 4.5
Laird Connectivity Solutions Support Center:
http://ews-support.lairdtech.com
www.lairdtech.com/ramp
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Americas: +1-800-492-2320
Europe: +44-1628-858-940
Hong Kong: +852 2923 0610
REVISION HISTORY
Version
Date
Changes
Approved By
1.0
Initial Release
Chris Downey
1.1
10/2012
Major changes and revisions throughout document
Chris Downey
2.0
04/5/2013
Major changes and revisions; updated format and
data
Chris Downey
3.0
--
--
Chris Downey
4.0
--
--
Chris Downey
4.1
10 Dec 2013
Updated download instructions for Laird
Configuration Utility in section How do I configure
Sync to Channel?
Chris Downey
4.2
11 Dec 2013
Separated into two separate docs (Hardware
Integration Guide and User Guide).
Added a Related Documents section.
Sue White
4.3
6 Feb 2013
Fixed return data for EEPROM Byte Write.
Chris Downey
4.4
15 Apr 2015
Updated contact information and links to new
website.
Sue White
4.5
18 May 2017
Removed references to EOL part numbers
Jonathan Kaye
FCC Notice
WARNING: This device complies with Part 15 of the FCC Rules. Operation is subject to the
following two conditions: (1) This device may not cause harmful interference and (2) This
device must accept any interference received, including interference that may cause
undesired operation.
RF Exposure/Installation Instructions
WARNING: To satisfy FCC RF exposure requirements for mobile transmitting devices, this
equipment must be professionally installed such that the end user is prevented from
replacing the antenna with a non-approved antenna. The end user should also be prevented
from being within 20cm of the antenna during normal use with the exception of hands,
feet, wrists and ankles.
The preceding statement must be included as a CAUTION statement in manuals for OEM
products to alert users on FCC RF Exposure compliance.
Caution: Any change or modification not expressly approved by Laird could void the user’s authority to
operate the equipment.
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CONTENTS
AC4490 RF Transceiver ................................................................................................................................. 4
Overview .................................................................................................................................................... 4
Features ........................................................................................................................................................ 4
Theory of Operation .................................................................................................................................... 5
RF Architecture........................................................................................................................................... 5
Modes of Operation ................................................................................................................................... 5
AC4490 Configuration ................................................................................................................................. 8
AT Commands ........................................................................................................................................... 8
Command Descriptions ............................................................................................................................ 10
API Control .............................................................................................................................................. 20
EEPROM Parameters .................................................................................................................................. 22
Appendix I: API .......................................................................................................................................... 29
Appendix II: Sync-to-Channel .................................................................................................................... 34
Sync to Channel - What is it and do I need to use it? ............................................................................... 34
How do I configure Sync to Channel? ...................................................................................................... 36
I’ve configured my radios, what’s next? ................................................................................................... 42
Related Documents and Files .................................................................................................................... 45
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AC4490 RF TRANSCEIVER
The compact AC4490 900 MHz transceiver can replace miles of cable in harsh industrial environments. Using
field-proven frequency hopping spread spectrum (FHSS) technology which needs no additional FCC licensing
in the Americas, OEMs can easily make existing systems wireless with little or no RF expertise.
Overview
The AC4490 is a cost effective, high performance, frequency hopping spread spectrum transceiver designed
for integration into OEM systems operating under FCC part 15.247 regulations for the 900 MHz ISM band.
AC4490 transceivers provide an asynchronous TTL level serial interface for OEM Host communications, which
include both system and configuration data. The Host supplies system data for transmission to other Host(s).
Configuration data is stored in the on-board EEPROM. All frequency hopping, synchronization, and RF system
data transmission/reception is performed by the transceiver.
To boost data integrity and security, the AC4490 uses Laird’s field-proven FHSS technology featuring optional
Data-Encryption Standards (DES). Fully transparent, these transceivers operate seamlessly in serial cable
replacement applications.
AC4490 transceivers can operate in Point-to-Point, Point-to-Multipoint, Client-Server, or Peer-to-Peer
architecture. One transceiver is configured as a server with one or many client-configured transceivers
synchronized to it. To establish synchronization between transceivers, the server emits a beacon; upon
detecting a beacon an RF link is established and a GPIO is toggled to signify to the host that the link is active.
This document contains information about the hardware and software interface between a Laird AC4490
transceiver and an OEM Host. Information includes the theory of operation, specifications, interface definition,
configuration information and mechanical drawings. The OEM is responsible for ensuring the final product
meets all appropriate regulatory agency requirements listed herein before selling any product.
Additionally, this document contains a list of Related Documents and Files.
Note: Unless mentioned by name, the AC4490 module is referred to as the “radio” or “transceiver”.
Individual naming is used to differentiate product specific features. The host (PC / Microcontroller /
Any device to which the AC4490 module is connected) will be referred to as “OEM Host”.
FEATURES
Networking and Security
Generic I/O digital lines and integrated DAC/ADC
functions
Retries and Acknowledgements
API Commands to control packet routing and
acknowledgement on a packet-by-packet basis
Frequency Hopping Spread Spectrum for security
and interference rejection
Customizable RF Channel number and system ID
Dynamic link analysis, remote radio discovery
Low latency and high throughput
Hardware Protocol Status monitoring
Easy to Use
Continuous 76.8 Kbps RF data stream
Software selectable interface baud rates
from 1200 bps to 115.2 Kbps
Low cost, low power and small size ideal for
high volume, portable and battery powered
applications
All modules are qualified for Industrial
temperatures (-40° C to 85° C)
Advanced configuration available using AT
commands
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THEORY OF OPERATION
RF Architecture
The AC4490 utilizes a server-client network architecture where all clients synchronize their hopping to the
server. The server transmits a beacon during the first 20 milliseconds of every hop. The client transceivers
listen for this beacon and, upon hearing it, assert their In_Range Low and synchronize hops with the server.
Each network consists of only one server. There should never be two servers on the same RF channel number
in the same coverage area because the interference between the two servers will severely hinder RF
communications. For those applications requiring collocated servers, Laird recommends using the Sync-to-
Channel feature, further explained in Appendix I: Sync-to-Channel.
Modes of Operation
The AC4490 has three different operating modes:
Transmit mode
Receive mode
Command mode
If the transceiver is not communicating with another radio, it is in Receive mode actively listening for a
beacon from the server. If the client determines that the beacon is from a server operating on the same RF
channel and system ID, it responds by asserting In_Range Low. A transceiver enters Transmit or Command
mode when the OEM host sends data over the serial interface. The state of the CMD Data pin (Pin 17) or
the data contents determine which of the two modes the transceiver enters.
Transmit Mode
All packets sent over the RF are either Addressed or Broadcast packets. Broadcast and Addressed delivery can
be controlled dynamically with the API Control feature set, which can be enabled in the EEPROM
configuration. To prohibit transceivers from receiving broadcast packets, Unicast Only can be enabled.
Addressed
Packets
When sending an addressed packet, the RF packet is sent only to the receiver specified in the
destination address. To increase the odds of successful delivery, the packet uses transmit
retries. Transparent to the OEM host, the sending radio sends the RF packet to the intended
receiver. If the receiver receives the packet error-free it returns an RF Acknowledgement in
the same 20 ms hop. If a Receive Acknowledgement is not received, the radio uses a
transmit retry to resend the packet. This continues until either an acknowledgement is
received or all transmit retries are used. The received packet is only sent to the OEM Host if
and when it is received free of errors.
Broadcast
Packets
When sending a broadcast packet, the RF packet is sent to every eligible transceiver on the
network. To increase the odds of successful delivery, it uses broadcast attempts. Transparent
to the OEM host, the sending radio sends the RF packet to the intended receiver(s).
Unlike Transmit Retries, all broadcast attempts are used, regardless of when the RF packet is
actually received. RF acknowledgments are not sent or received when a broadcast packet is
transmitted. If the packet is received on the first attempt, the receiver ignores the remaining
broadcast attempts. The received packet is only sent to the OEM host if and when it is
received free of errors.
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Receive Mode
When a transceiver is not in Transmit or Command mode, it is in Receive mode listening for data. While in
Receive mode, subsequent data of up to 80 bytes can be received every hop (20 ms).
Command Mode
A radio enters Command mode when data is received over the serial interface from the OEM host and
contains the AT+++ (Enter AT Command mode) command or when the state of the CMD/DATA pin is
transitioned low. Once in Command mode, the radio interprets all data received as command data.
Command data can be either EEPROM configuration or on-the-fly commands.
Figure 1: Pending RF Buffer Flow
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AC4490 CONFIGURATION
AT Commands
The AT Command mode implemented in the AC4490 creates a virtual version of the Command/Data pin. The
“Enter AT Command Mode” Command asserts this virtual pin Low (to signify Command Mode) and the “Exit
AT Command Mode” Command asserts this virtual pin High (to signify Data). Once this pin has been asserted
Low, all On-the-Fly CC Commands documented in the manual are supported.
Note: The Command/Data RX Disable feature can be enabled in firmware versions 8.6+. When enabled in
EEPROM, the radio disables the RF receiver while pin 17 (Command/Data) is Low. To ensure that
the radio is not in the middle of transmitting data to the OEM Host, the host should be prepared
to receive data for up to 20ms after taking pin 17 Low.
On-the-Fly Control
Commands
The AC4490 transceiver contains static memory that holds many of the parameters
that control the transceiver operation. Using the “CC” command set allows many of
these parameters to be changed during system operation. Because the memory
these commands affect is static, when the transceiver is reset, these parameters will
revert back to the settings stored in the EEPROM. While in CC Command mode
using pin 17 (Command/Data), the RF interface of the transceiver is still active.
Therefore, it can receive packets from remote transceivers while in CC Command
mode and forward these to the OEM Host.
AT Command Mode
While in CC Command mode using AT Commands, the RF interface of the
transceiver is active, but packets sent from other transceivers will not be received.
The transceiver uses Interface Timeout/RF Packet Size to determine when a CC
Command is complete. Therefore, there should be no delay between each character
as it is sent from the OEM Host to the transceiver or the transceiver will not
recognize the command.
The link between the OEM host and the transceiver does not need to resync when
exiting Command Mode. Acknowledgements will be sent while in Command Mode,
but the packet will be dumped on the receiving end. However, if an RF packet is
received before the Interface Timeout expires on a CC Command, the transceiver will
send the packet to the OEM Host before sending the CC Command response.
When an invalid command is sent, the radio scans the command to see if it has a
valid command followed by bytes not associated with the command, in which case
the radio discards the invalid bytes and accepts the command. In all other cases, the
radio returns the first byte of the invalid command to the user and discards the rest.
Table 1: Command Quick Reference
Command Name
Command (All Bytes in Hex)
Return (All Bytes in Hex)
Enter Command Mode
0x41
0x54
0x2B
0x2B
0x2B
0x0D
0xCC
0x43
0x4F
0x4D
Exit Command Mode
0xCC
0x41
0x54
0x4F
0x0D
-
0xCC
0x44
0x41
0x54
Status Request
0xCC
0x00
0x00
-
-
-
0xCC
Firmware
Version
0x00: Server
0x01: Client in range
0x03: Out of range
Change Channel
0xCC
0x02
New Channel
-
-
0xCC
New Channel
-
Change Server/Client
0xCC
0x03
0x00: Server
0x03: Client
-
-
0xCC
Firm-ware
Version
0x00: Server
0x03: Client
Change Sync
Channel
0xCC
0x05
New Sync
Channel
-
-
0xCC
New Sync
Channel
-
-
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Command Name
Command (All Bytes in Hex)
Return (All Bytes in Hex)
Sleep Walk Power
Down
0xCC
0x06
-
-
-
-
0xCC
Channel
-
-
Sleep Walk Wake Up
0xCC
0x07
-
-
-
-
0xCC
Channel
-
-
Broadcast
Packets
0xCC
0x08
0x00: Addressed
0x01: Broadcast
-
0xCC
0x00 or
0x01
-
-
Write Destination
Address
0xCC
0x10
Byte 4 of
Dest. MAC
Byte 5
Byte 6
0xCC
Byte 4 of
Dest.MAC
Byte 5
Byte 6
Read Destination
Address
0xCC
0x11
-
-
-
-
0xCC
Byte 4 of
Dest. MAC
Byte 5
Byte 6
Forced Calibration
0xCC
0x12
0x00
0x00
-
-
0xCC
Firm-ware
Version
0x00: Server in
Normal Operation
0x01: Client in
Normal Operation
0x02: Server in
Acquisition Sync
0x03: Client in
Acquisition Sync
Auto Destination
0xCC
0x15
bit-0: Auto Destination
bit-1: Auto Channel
bit-4: Enable Auto Destination
bit-5: Enable Auto Channel
0xCC
bit-0: Auto Destination
bit1: Auto Channel
bits-2-7: 0
Read Digital Inputs
0xCC
0x20
-
-
-
-
0xCC
bit-0: GI0
bit-1: GI1
-
-
Read ADC
0xCC
0x21
0x01: AD In
0x02: Temp
0x03: RSSI
-
-
0xCC
MSB of 10
bit ADC
LSB of 10 bit ADC
Report Last Valid RSSI
0xCC
0x22
-
-
-
-
0xCC
RSSI
-
-
Write Digital
Outputs
0xCC
0x23
bit-0: GO0
bit-1: GO1
-
-
0xCC
bit-0: GO0
bit-1: GO1
-
-
Write DAC
0xCC
0x24
Update
Period
Duty
Cycle
-
-
0xCC
Update
Period
Duty
Cycle
-
Set Max Power
0xCC
0x25
New Max Power
-
0xCC
Max Power
-
-
Report Last Packet
RSSI
0xCC
0x26
-
-
-
-
0xCC
RSSI
-
-
Long Range Mode1
0xCC
0x27
0x00: Normal Mode (Disabled)
0x01: Long Range Mode (Enabled)
0xCC
0x00: Normal Mode (Disabled)
0x01: Long Range Mode (Enabled)
Transmit Buffer Empty
0xCC
0x30
-
-
-
-
0xCC
0x00
-
-
Disable Sync to
Channel
0xCC
0x85
-
-
-
-
0xCC
Channel
-
-
Deep Sleep Mode
0xCC
0x86
-
-
-
-
0xCC
Channel
-
-
Enter Probe
0xCC
0x8E
0x00: Enter Probe
0x01: Exit Probe
-
0xCC
0x00 or
0x01
-
-
Read Temperature
0xCC
0xA4
-
-
-
-
0xCC
Temp (C)
-
-
Read Temperature at
last calibration
0xCC
0xA5
-
-
-
-
0xCC
Temp (C)
EEPROM Byte Read
0xCC
0xC0
Start Address
Length
0xCC
Start
Address
Length
Data
EEPROM Byte Write
0xCC
0xC1
Start Address
Length
Data
Starting Address
Length
Data
written
Soft Reset
0xCC
0xFF
-
-
-
-
-
-
-
-
1. Available only on AC4490LR-1000 transceivers.
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Command Descriptions
Enter AT Command Mode
Prior to sending this command, the OEM Host must ensure that the transceiver’s RF transmit buffer is empty.
If the buffer is not empty, the radio will interpret the command as data and it will be sent over the RF. This
can be accomplished by waiting up to one second between the last packet and the AT command.
Note: RF Packet Size must be set to a minimum of 6 to use this command.
Command: <0x41> <0x54> <0x2B> <0x2B> <0x2B> <0x0D>
Number of Bytes Returned: 4
Response: <0xCC> <0x43> <0x4F> <0x4D>
Exit AT Command Mode
The OEM Host should send this command to exit AT Command mode and resume normal operation.
Command: <0xCC> <0x41> <0x54> <0x4F> <0x0D>
Number of Bytes Returned: 4
Response: <0xCC> <0x44> <0x41> <0x54>
Status Request
The OEM Host issues this command to request the status of the transceiver.
Command: <0xCC> <0x00> <0x00>
Number of Bytes Returned: 3
Response: <0xCC> <Version> <Status>
Parameter Range:
<Version> = Firmware version of radio
<Status> = 0x00: Server
0x01: Client in Range
0x03: Client out of Range
Change Channel
The OEM Host issues this command to change the channel of the transceiver.
Command: 0xCC 0x02 <Channel>
Number of Bytes Returned: 2
Response: 0xCC <Channel>
Parameter Range: <Channel> = RF Channel in use
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Change Server/Client
The OEM Host issues this command to change the mode of the transceiver from server to client and vice
versa.
Command: <0xCC> <0x03> <Mode>
Number of Bytes Returned: 3
Response: <0xCC> <Version> <Mode>
Parameter Range:
<Mode> = 0x00: Server
0x03: Client
<Version> = Firmware version of radio
Change Sync Channel
The OEM Host issues this command to change the sync channel byte and enable sync to channel. See
Appendix I: Sync-to-Channel for more information.
Note: Valid only for server transceivers.
Command: <0xCC> <0x05> <Channel>
Number of Bytes Returned: 3
Response: <0xCC> <Channel>
Parameter Range: <Channel> = Sync Channel
Sleep Walk Power-Down
After the host issues this command, the client transceiver will issue its In_Range line logic high after entering
power down. A client in Power Down will remain in sync with a server for a minimum of 2 minutes. To
maintain synchronization with the server, the client should re-sync at least once every 2 minutes. This is done
by sending the Power Down Wake Up command and waiting for the In_Range line to issue logic low. Once
this occurs, the client is in sync with the server and can be put back into power-down mode.
Note: This command is valid only for client transceivers.
Command: <0xCC> <0x06>
Number of Bytes Returned: 2
Response: <0xCC> <Channel>
Parameter Range: <Channel> = RF Channel currently being used
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Sleep Walk Power-Down Wake Up
The OEM Host issues this command to bring the client transceiver out of Power Down mode.
Note: This command is valid only for client transceivers.
Command: <0xCC> <0x07>
Number of Bytes Returned: 2
Response: <0xCC> <Channel>
Parameter Range: <Channel> = RF Channel currently being used
Broadcast Packets
The OEM Host issues this command to change the transceiver operation between Addressed Packets and
Broadcast Packets. If Addressed Packets are selected, the transceiver will send all packets to the transceiver
designated by the Destination Address programmed in the transceiver. If Broadcast Packets are selected, the
transceiver will send its packets to all transceivers on that network.
Command: <0xCC> <0x08> <Mode>
Number of Bytes Returned: 2
Response: <0xCC> <Mode>
Parameter Range: <Mode> = 0x00: Addressed
0x01: Broadcast
Write Destination Address
The OEM Host issues this command to the transceiver to change the Destination Address.
Note: Only the three Least Significant Bytes of the MAC Address are used for packet delivery.
Command: <0xCC> <0x10> <MAC3> <MAC2> <MAC1>
Number of Bytes Returned: 4
Response: <0xCC> <MAC3> <MAC2> <MAC1>
Parameter Range: <MAC> = 0x00 - 0xFF corresponding to 3 LSB’s of destination MAC Address
Read Destination Address
The OEM Host issues this command to the transceiver to read the destination address.
Note: Only the three Least Significant Bytes of the MAC Address are used for packet delivery.
Command: <0xCC> <0x11>
Number of Bytes Returned: 4
Response: <0xCC> <MAC3> <MAC2> <MAC1>
Parameter Range: <MAC> = 0x00 - 0xFF corresponding to 3 LSB’s of destination MAC Address
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Auto Calibration (Forced Recalibration)
When enabled, Auto Calibrate causes the radio to measure the temperature every 30 to 60 seconds. If the
temperature changes more than 30ºC from the last calibration, the radio will initiate a recalibration.
During the recalibration, the radio will not assert CTS high. Recalibration can take up to 3 seconds and the
command response will not be sent to the OEM Host until recalibration is complete.
Note: If Auto Calibration is
disabled
, the CL4490 radio may fail to lock onto frequency. If it does, the
radio timeouts after 5 ms and performs a recalibration.
Command: <0xCC> <0x12> <0x00> <0x00>
Number of Bytes Returned: 3
Response: <0xCC> <Version> <Status>
Parameter Range: <Version> = Firmware version of radio
<Status> = 0x00: Server in range
0x01: Client in range
0x02: Server out of range
0x03: Client out of range
Auto Destination/Auto Channel
The Host issues this command to change the Auto Destination & Auto Channel settings. When issuing this
command, the Auto Destination/Auto Channel settings is only changed if the corresponding enable bit is set.
Command: <0xCC> <0x15> <Auto Dest>
Number of Bytes Returned: 2
Response: <0xCC> <Auto Dest>
Parameter Range:
<Auto Dest>= bit 7: Ignored
bit 6: Ignored
bit 5: Enable Auto Chan. Modification
bit 4: Enable Auto Dest. Modification
bit 3: Ignored
bit 2: Ignored
bit 1: Auto Channel
bit 0: Auto Destination
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Read Digital Inputs
The OEM Host issues this command to read the state of both digital input lines.
Command: <0xCC> <0x20>
Number of Bytes Returned: 2
Response: <0xCC> <Digital In>
Parameter Range:
<Digital In> = bit-0: GI0
bit-1: GI1
Read ADC
The OEM Host issues this command to read any of the three onboard 10-bit A/D converters. Because the RF is
still active in On-the-Fly Command Mode, the transceiver will not process the command until there is no
activity on the network. The Read RSSI command is therefore useful for detecting interfering sources but will
not report the RSSI from a remote transceiver on the network. The equations for converting these 10 bits into
analog values are as follows:
Analog Voltage = (10 bits / 0x3FF) * 3.3 V
Temperature (o C) = ((Analog Voltage - 0.3) / 0.01) - 30
Instantaneous RSSI value (dBm) = -105 + (0.22 * (0x3FF - 10 bits))
Command: <0xCC> <0x21> <Port>
Number of Bytes Returned: 3
Response: <0xCC> <Hi ADC> <Lo ADC>
Parameter Range:
<Port> = 0x00: AD In
0x01: Temperature
0x02: Instantaneous RSSI
<Hi ADC> = MSB of requested 10-bit ADC value
<Lo ADC> = LSB of requested 10-bit ADC value
Report Last Valid RSSI
Since RSSI values are only valid when the local transceiver is receiving an RF packet from a remote transceiver,
instantaneous RSSI can be tricky to use. Therefore, the transceiver stores the most recent valid RSSI value as
measured the last time the transceiver received a packet or beacon. The Host issues this command to retrieve
that value.
Note: This value will default to 0xFF on a client and 0x00 on a server if no valid RSSI measurement has
been made since power-up.
Command: <0xCC> <0x22>
Number of Bytes Returned: 2
Response: <0xCC> <Last Valid RSSI>
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Table 2: Received Signal Strength
RSSI (dBm)
Hex Value
RSSI (dBm)
Hex Value
-92
C0
-72
63
-91
BC
-71
5F
-90
BB
-70
5B
-89
B9
-69
58
-88
B8
-68
54
-87
AE
-67
4F
-86
A9
-66
4B
-85
A2
-65
47
-84
92
-64
43
-83
8D
-63
3D
-82
86
-62
2A
-81
82
-60
25
-80
7D
-58
1A
-79
79
-56
16
-78
75
-54
13
-77
72
-52
11
-76
6F
-50
0E
-75
6B
-48
0D
-74
68
-46
0C
-73
66
-44
0B
Note: The receiver is saturated after -45 dBm and cannot accurately measure the RSSI above -45 dBm.
Write Digital Outputs
The OEM Host issues this command to write both digital output lines to particular states.
Note: This command should only be used when Protocol Status (0xC2) is not set to 0xE3.
Command: <0xCC> <0x23> <Digital Out>
Number of Bytes Returned: 2
Response: <0xCC> <Digital Out>
Parameter Range:
<Digital Out>= bit-0: GO0
bit-1: GO1
Write DAC
The OEM Host issues this command to write DA_Out to a particular voltage. The transceiver uses a PWM
(Pulse Width Modulator) to generate the analog voltage. The theory behind a PWM is that a binary pulse is
generated with a fixed rate (<Data 1>) and duty cycle (<Data 2>). As such, this pin toggles between High &
Low. This signal is filtered via an on-board R-C circuit and an analog voltage is generated.
Duty cycle specifies the ratio of time in one cycle that the pulse spends High proportionate to the amount of
time it spends Low. So, with a duty cycle of 50% (0x80), the pulse is High 50% of the time and Low 50% of
the time; therefore the analog voltage would be half of 3.3V or 1.65V. A broad filter has been implemented
on the transceiver and there is no advantage to using a slower update period. Generally, a faster update
period is preferred.
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Command: <0xCC> <0x24> <Data1> <Data2>
Number of Bytes Returned: 3
Response: <0xCC> <Data1> <Data2>
Parameter Range: <Data1> = Period of PWM, Hex value
<Data2> = Duty Cycle of PWM, Hex value
Data1 = (Tperiod * 14.74566) - 1 ; Where Tperiod == Period of the PWM in seconds
255 Data1 value is then converted from decimal to hex
Data2 = DCpercentage * 255 ; Where DCpercentage == duty cycle of the PWM in decimal percent (50% = 0.5)
Note: The duty cycle is represented at this pin as an analog voltage. 50% duty cycle is half of 3.3V or
1.65V.
Set Max Power
The OEM Host issues this command to limit the maximum transmit power emitted by the transceiver. This can
be useful to minimize current consumption and satisfy certain regulatory requirements.
Note: The radios are shipped at maximum allowable power.
Command: <0xCC> <0x25> <Max Power>
Number of Bytes Returned: 2
Response: <0xCC> <Max Power>
Parameter Range: <Max Power>= New Max Power setting
Output Power
Table 3: AC4490-200
EEPROM Value
(Hex)
Current (mA)
dBm
mW
0
61
-22
0.01
1
64
-9
0.13
2
65
-3
0.5
3
66
1
1.26
4
67.5
4
2.51
5
70
7
5.01
6
73
9
7.94
7
77
10.5
11.22
8
83
12
15.85
9
88
13.5
22.39
A
93.5
14.5
28.18
B
99
15.5
35.48
C
105
16.5
44.67
D
110.5
17
50.12
E
114.5
17.5
56.23
F
117.5
18.5
70.79
1E
126
19.5
89.13
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EEPROM Value
(Hex)
Current (mA)
dBm
mW
60
127.5
20
100
Table 4: AC4490-1000
EEPROM Value
(Hex)
Current
(mA)
dBm
mW
0
430
-1
0.79
1
430
9
7.94
2
470
14
25.12
3
520
16.5
44.67
4
560
19
79.43
5
650
20.5
112.2
6
740
22
158.49
7
780
23
199.53
8
870
24.5
281.84
9
950
25
316.23
A
1000
26
398.11
B
1080
26.5
446.68
C
1130
27
501.19
D
1170
27.5
562.34
E
1260
28
630.96
F
1300
28
743
Long Range Mode
The OEM Host issues this command to temporarily enable or disable Long Range Mode in the transceiver.
Note: Only available on AC4490LR-1000 transceivers with firmware v6.7+.
Command: <0xCC> <0x27>
Number of Bytes Returned: 2
Response: <0xCC> <Mode>
Parameter Range:
<Mode> = 0x00: Disable Long Range Mode
0x01: Enable Long Range Mode
Transmit Buffer Empty
The OEM Host issues this command to determine when the RF transmit buffer is empty. The Host will not
receive the transceiver response until that time.
Command: <0xCC> <0x30>
Number of Bytes Returned: 2
Response: <0xCC> <0x00>
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Disable Sync-to-Channel
The OEM Host issues this command to disable Sync-to-Channel mode. See Appendix I: API for more
information.
Note: This command is valid only for servers.
Command: <0xCC> <0x85>
Number of Bytes Returned: 2
Response: <0xCC> <Channel>
Parameter Range: <Channel> = RF Channel currently being used
Deep Sleep Mode
The OEM Host issues this command to put the transceiver into Deep Sleep mode. Once in Deep Sleep mode,
the transceiver disables all RF communications and will not respond to any further commands until being
reset or power-cycled.
Note: This command is valid for both servers and clients.
Command: <0xCC> <0x86>
Number of Bytes Returned: 2
Response: <0xCC> <Channel>
Parameter Range: <Channel> = RF Channel currently being used
Read Temperature
The OEM Host issues this command to read the onboard temperature sensor. The transceiver reports the
temperature in o C where 0x00 - 0x50 corresponds to 0 - 80 o C and 0xD8 - 0x00 corresponds to - 40 - 0 o C.
Command: <0xCC> <0xA4>
Number of Bytes Returned: 2
Response: <0xCC> <Temp>
Parameter Range: <Temp> = Temperature of module
Read Temperature at Last Calibration
The OEM Host issues this command to read the temperature of the radio at the time of its last calibration.
The transceiver reports the temperature in o C where 0x00 - 0x80 corresponds to 0 - 80o C and where 0xD8 -
0x00 is the two’s complement representation corresponding to -40 - 0 o C.
Note: 0xD8 is a twos complement representation of -40 – 0.
Command: <0xCC> <0xA5>
Number of Bytes Returned: 2
Response: <0xCC> <Temp>
Parameter Range: <Temp> = Temperature at last calibration
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Probe
When the OEM Host issues this command, the transceiver sends out a query every 500 ms. The transceivers
randomly choose a query to respond to. After responding to a probe, the transceiver will wait at least 10
seconds before responding to another probe.
Note: This command can only be sent from a server radio.
Command: <0xCC> <0x8E> <Probe>
Number of Bytes Returned: 2
Response: <0xCC> <Probe>
Parameter Range:
<Probe> = 0x00: Disable Probe Mode
0x01: Enable Probe Mode
Transceiver’s Response
Upon hearing the remote transceiver’s probe acknowledge, the transceiver sends a response to the OEM Host.
Command: N/A
Number of Bytes Returned: 5
Response: <0xCC> <Data> <MAC3> <MAC2> <MAC1>
Parameter Range:
<Data> = bit-7: 0 Client
bit-7: 1 Server
bits 6-0: RF Channel
EEPROM Byte Read
Upon receiving this command, a transceiver will respond with the desired data from the addresses requested
by the OEM Host. See EEPROM Parameters.
Command: <0xCC> <0xC0> <Start> <Length>
Number of Bytes Returned: 4+
Response: <0xCC> <Start> <Length> <Data>
Parameter Range:
<Start> = Address to begin reading from
<Length> = Length of bytes to read
<Data> = Requested data
EEPROM Byte Write
Upon receiving this command, a transceiver will write the data byte to the specified address but will not echo
it back to the OEM Host until the EEPROM write cycle is complete (up to 10 ms).
Multiple byte writes of up to 128 bytes are allowed. An EEPROM boundary exists between addresses 0x7F
and 0x80. No single EEPROM write command shall write to addresses on both sides of that EEPROM
boundary. See EEPROM Parameters.
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Note: Only the last byte written will be displayed in the command response.
Command: <0xCC> <0xC1> <Start> <Length> <Data>
Number of Bytes Returned: 4+
Response: <Starting Address> <Length> <Data written>
Parameter Range:
<Start> = Address to begin writing from
<Length> = Length of bytes to write
<Data> = Last byte of data written
Reset
The OEM Host issues this command to perform a soft reset of the transceiver. Any transceiver settings
modified by CC commands will revert to the default values stored in the EEPROM.
Command: <0xCC> <0xFF>
Number of Bytes Returned: None
Response: None
API Control
API Control is a powerful feature offered by the AC4490. When enabled, the API Receive Packet, API
Transmit Packet, API Send Data Complete and Enhanced API Receive Packet features provide dynamic packet
routing and packet accounting ability to the OEM host, thereby eliminating the need for extensive
programming on the OEM host side. API operation utilizes specific packet formats; specifying various vital
parameters used to control radio settings and packet routing on a packet-by-packet basis. The API features
can be used in any combination that suits the OEM’s specific needs.
Receive API Packet
Note: Implemented in firmware v.6.3 and later.
By default, the source MAC is not included in the received data string sent to the OEM host. For applications
where multiple radios are sending data, it may be necessary to determine the origin of a specific data packet.
Receive API Packet can be enabled to determine the sender of a message. This causes the receiving radio to
add a header to the received packet detailing the length of the data packet and the sender’s MAC address.
The format of the Receive API Packet is:
0x83
Payload Data Length
Sender’s MAC
Payload Data
Note: If Receive API is enabled, the Enhanced API Receive feature should be disabled by clearing bit-0 of
the Enhanced API control byte, EEPROM address 0xC6.
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Enhanced API Receive Packet
Note: Implemented in firmware v.6.7 and later.
When Enhanced API Receive Packet is enabled, all packets received by the transceiver include the MAC
address of the source radio as well as an RSSI indicator which can be used to determine the link quality
between the two. API Receive Packet is enabled when bit-0 of the Enhanced API Control byte is enabled.
Upon receiving a packet the radio sends its OEM Host the packet in the following format:
0x81
Payload Data Length (0x01 – 0x50)
Laird Use
RSSI*
Source MAC
(2, 1, 0)
Payload Data
Note: When both API Send Data Complete and API Receive Packet are enabled, the Send Data Complete
will be received before the transceiver sees the Receive API Packet. This may be reversed when the
API Send Data Complete is missed and is being resent after the API Receive Packet is received.
Note: If Enhanced API Receive is enabled, the Receive API feature should be disabled by setting EEPROM
byte 0xC1 to 0xFF.
API Transmit Packet
Note: Implemented in firmware v6.7 and later.
API Transmit Packet is a powerful command that allows the OEM host to dynamically send data to a single or
multiple (broadcast) transceiver(s) on a packet-by-packet basis. API Transmit Packet is enabled when bit-1 of
the Enhanced API Control byte (EEPROM byte 0xC6) is enabled. The OEM host must use the following format
to transmit a packet over the RF when using Transmit API packets:
0x81
Payload Data Length
(0x01 – 0z50)
Laird Use
Transmit Retries/
Broadcast Attempts
Destination MAC
(2, 1, 0)
Payload Data
If the OEM Host does not encode the header correctly, the transceiver sends the entire string (up to 80
bytes) and looks for the header in the next data.
Although the seven bytes of overhead are not sent over the RF, they are kept in the buffer until the
packet is sent. Keep this in mind so as not to overrun the 256-byte buffer.
Setting the Destination MAC to 0xFF 0xFF 0xFF broadcasts the packet to all available transceivers.
Note: If the OEM host does not properly encode the header of the Tx API packet, the string (up to 80
bytes) is sent to the MAC address from the header of the last known good Tx API encoded packet.
API Send Data Complete
Note: Implemented in v6.7 of the firmware and later.
API Send Data complete can be used as a software acknowledgement indicator. When a radio sends an
addressed packet, it looks for a received acknowledgement (transparent to OEM host). If an
acknowledgement is not received, the packet is retransmitted until one is received or all retries are used.
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API Send Data Complete is enabled when bit-2 of the Enhanced API Control byte (EEPROM byte 0xC6) is
enabled. The transceiver sends the OEM host the following data upon receiving an RF acknowledge or
exhausting all attempts:
0x82
Laird Use
RSSI*
0x00: Failure
0x01: Success
RSSI* is how strong the local transceiver heard the remote transceiver.
Successful RF Acknowledge updates the Success/Failure bit.
A success is always displayed when sending broadcast packets (after all broadcast attempts have been
exhausted).
EEPROM PARAMETERS
The OEM Host can program various parameters that are stored in EEPROM which become active after a
power-on reset. Table 5 gives the locations and descriptions of the parameters that the OEM Host can read or
write. Factory default values are also shown.
WARNING: Do not write to any EEPROM addresses other than those listed below. Do not copy one
transceiver’s EEPROM to another transceiver as doing so may cause the transceiver to malfunction.
Only the Configuration Utility should be used to copy one configuration into another transceiver.
Table 5: EEPROM Parameters
Parameter
EEPROM
Address
Length
(Bytes)
Range
Default
Description
Product ID
0x00
40
Product identifier string. Includes revision
information for software and hardware.
Page Refresh
0x3D
1
0x01 -
0xFF
0x18
Specifies the maximum amount of time a
transceiver will report In-Range without
having heard a server’s beacon (equal to
hop period * value).
Note: Do not set to 0x00.
Stop Bit Delay
0x3F
1
0x00 -
0xFF
0xFF
For systems employing Parity, the serial stop
bit might come too early. Stop Bit Delay
controls the width of the last bit before the
stop bit occurs.
0xFF = Disable Stop Bit Delay (12 µs)
0x00 = (256 * 1.6 µs) + 12 µs
0x01 - 0xFE = (value * 1.6 µs) + 12 µs
Channel
Number
0x40
1
0x00 -
0x37
1x1: 0x00
200: 0x00
1000: 0x10
Set 0 = 0x00 - 0x0F (US/Canada): 1x1/200
Set 1 = 0x10 - 0x2F (US/Canada): 1x1/1000
Set 2 = 0x30 - 0x37 Australia:
1x1/200/1000
Server/Client
Mode
0x41
1
0x01 -
0x02
0x02
0x01 = Server
0x02 = Client
Baud Rate
Low
0x42
1
0x00 -
0xFF
0xFC
Low byte of the interface baud rate. Default
baud rate is 57600.
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Parameter
EEPROM
Address
Length
(Bytes)
Range
Default
Description
Baud Rate
High
0x43
1
0x00
0x00
High byte of interface baud. Always 0x00.
Control 0
0x45
1
0x00 -
0xFF
0x14
Settings are:
bit-7: One Beacon Mode
0 = Disable One Beacon Mode
1 = Enable One Beacon Mode
bit-6: DES Enable
0 = Disable Encryption
1 = Enable Encryption
bit-5: Sync-to-Channel
0 = Disable Sync-to-Channel
1 = Enable Sync-to-Channel
bit-4: Laird Use Only
bit-3: Laird Use Only
bit-2: Laird Use Only
bit-1: RF Delivery
0 = Transmit using Addressed packets
1 = Transmit using Broadcast packets
bit-0: Laird Use Only
Frequency
Offset
0x46
1
0x00 -
0xFF
0x01
Protocol parameter used in conjunction
with Channel Number to satisfy unique
regulations.
CMD /Data
RX Disable
0x4B
1
0xE3,
0xFF
0xFF
oxE3 = Enable CMD /Data RX Disable
0xFF = Disable CMD /Data RX Disable
Transmit
Retries
0x4C
1
0x01 -
0xFF
0x10
Maximum number of times a packet is
transmitted when Addressed packets are
selected.
Note: Do not set to 0.
Broadcast
Attempts
0x4D
1
0x01 -
0xFF
0x04
Number of times each packet is transmitted
when Broadcast packets are selected.
Note: Do not set to 0.
API Control
0x56
1
0x00 -
0xFF
0x43
Settings are:
bit-7: Laird Use Only
bit-6: Laird Use Only
bit-5: Unicast Only
0 = Disable Unicast Only
1 = Enable Unicast Only
bit-4: Auto Destination
0 = Use destination address
1 = Use auto destination
bit-3: Client Auto Channel
0 = Disable Auto Channel
1 = Enable Auto Channel
bit-2: RTS Enable
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Parameter
EEPROM
Address
Length
(Bytes)
Range
Default
Description
0 = Ignore RTS
1 = Transceiver obeys RTS
bit-1: Duplex
0 = Half Duplex
1 = Full Duplex
bit-0: Auto Config
0 = Use EEPROM values
1 = Auto Configure values
Interface
Timeout
0x58
1
0x02 -
0xFF
0x04
Specifies a byte gap timeout, used in
conjunction with RF Packet Size to
determine when a packet coming over the
interface is complete (0.5 ms per
increment).
Sync Channel
0x5A
1
0x00 -
0xFF
0x01
Used to synchronize the hopping of
collocated systems to minimize
interference.
RF Packet Size
0x5B
1
0x01 -
0x80
0x80
Used in conjunction with Interface Timeout;
specifies the maximum size of an RF packet.
Note: Must be set to a minimum of 6 in
order to send the Enter AT command.
CTS On
0x5C
1
0x01 -
0xFF
0xD2
CTS will be deasserted (High) when the
transmit buffer contains at least this many
characters.
CTS On
Hysterisis
0x5D
1
0x00 -
0xFE
0xAC
Once CTS has been deasserted, CTS will
be reasserted (Low) when the transmit
buffer is contains this many or less
characters.
Max Power
0x63
1
0x00 -
0x60
Set in
Production
& can vary
Used to increase/decrease the output power.
Note: The transceivers are shipped at
maximum allowable power.
Modem
Mode
0x6E
1
0xE3,
0xFF
0xFF
oxE3 = Enable Modem Mode
0xFF = Disable Modem Mode
Parity
0x6F
1
0xE3,
0xFF
0xFF
0xE3 = Enable Parity
0xFF = Disable Parity
Note: Enabling parity cuts throughput and
the interface buffer size in half.
Destination ID
0x70
6
0x00 -
0xFF
0xFF
Specifies destination for RF packets
System ID
0x76
1
0x00 -
0xFF
0x01
Similar to network password. Radios must
have the same system ID to communicate
with each other.
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Parameter
EEPROM
Address
Length
(Bytes)
Range
Default
Description
MAC ID
0x80
6
0x00 -
0xFF
Factory programmed unique IEEE MAC
address.
Original Max
Power
0x8E
1
Set in
Production
& can vary
Copy of original max power EEPROM
setting. This may be referenced but should
not be modified.
Product ID
0x90
15
0x90 - 0x93: Product ID
0x94 - 0x95: Prefix (CL, CN, or AC)
0x96 - 0x99: Power (200M, 200A, 1000,
1x1)
Note: There will be a period in front of
the 1x1 to keep the field at four bytes.
0x9A - 0x9C: Interface (232, 485, TTL)
0x9D - 0x9E: Setup script (01 is stock)
0x9F: Reserved for future use; always 0xFF
Protocol
Status /
Receive ACK
0xC0
1
0xE3,
oxFF
oxFF
oxE3 = GO0 outputs the Protocol Status
and GO1 outputs the Received
Acknowledgement signal
0xFF = Disable Protocol Status / Receive
ACK
Receive API
0xC1
1
0xE3,
0xFF
0xFF
0xE3 = Enabled
0xFF = Disabled
Enhanced API
Ctrl.
0xC6
1
0xF8
Settings are:
bit-7: Enhanced API Control Enable
0 = Enable Enhanced API Control
1 = Disable Enhanced API Control
bit-6: Laird Use Only
bit-5: Laird Use Only
bit-4: Laird Use Only
bit-3: Laird Use Only
bit-2: Send Data Complete Enable
0 = Disable
1 = Enable
bit-1: API Transmit Packet Enable
0 = Disable
1 = Enable
bit-0: Enhanced API Receive Packet Enable
0 = Disable
1 = Enable
Auto
Calibrate
0xCC
1
0xE3,
0xFF
0xFF
oxE3 = Enable Auto Calibrate
0xFF = Disable Auto Calibrate
DES Key
0xD0
7
0x00 -
0xFF
56-bit Data Encryption key
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Radio Interface
The Radio Interface section manages the following settings:
Interface Timeout
Interface Timeout specifies a maximum byte gap between consecutive bytes.
When that byte gap is exceeded, the bytes in the transmit buffer are sent out
over the RF as a complete packet. Interface Timeout is adjustable in 0.5 ms
increments and has a tolerance of ±0.5 ms. The Interface Timeout should not be
set below 2. The default value for Interface Timeout is 0x04 (2 ms) and should be
adjusted accordingly when changing the transceiver baud rate.
RF Packet Size
RF Packet Size is used in conjunction with Interface Timeout to determine when
to delineate incoming data as an entire packet based on whichever condition is
met first. When the transceiver receives the number of bytes specified by RF
Packet Size without experiencing a byte gap equal to Interface Timeout, that
block of data is processed as a complete packet. Every packet the transceiver
sends over the RF contains extra header bytes not counted in the RF Packet Size. It
is much more efficient to send a few large packets than to send many short
packets.
CTS On/
CTS On Hysteresis
(Flow Control)
See Flow Control for more information.
Max Transmit
Retries
(For clients and
servers in Point-
to-Point networks
only)
This value represents the maximum number of times a particular data packet will
be transmitted unsuccessfully, or without an acknowledgement, before the
AC4490 discards the packet. The default value is 16 attempts. If communication
is lost and the client's Link LED is on, try increasing this value in small increments
until communication is reestablished.
Note: This value is always associated to client radios and server radios in Point
to Point Mobile. The valid range of values for this field is 1 to 255.
Broadcast
Attempts (Point-
to-Multipoint
only)
This value represents the number of times a data packet will be transmitted by a
transceiver in Broadcast Mode. The default value is 4 attempts. If communication
is lost and the clients' Link LED is on, try increasing this value in small increments
until communication is reestablished. Valid values for this field are 1 - 255.
Note: All Broadcast Attempts are used whether the packet was received
without error by the receiving radios or not.
Range Refresh
Range Refresh specifies the maximum amount of time a client reports in range
without hearing a server beacon. Each time the client hears a beacon, it resets its
Range Refresh timer. If the timer reaches zero, the client goes out of range, takes
In_Range pin High and enters acquisition mode to find the server once again.
The range refresh is equal to the hop period (20 ms) x Range refresh value.
Note: Range Refresh should not be set to 0x00.
Radio RF
The Radio RF section manages the following settings:
Client / Server
Designates AC4490 type. In each network, there must be only one server. All other
AC4490 units must be programmed as clients. The number of clients in the network
is not limited; however, if performance diminishes, consider additional RF Networks.
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RF Channel Number
A number that designates an independent network of AC4490 units. Up to 32
independent networks can be created.
Note: The valid range of values for this field is 16 to 47.
Sync to Channel
Sync-to-channel can be used to synchronize server frequency hopping and prevent
interference between collocated systems. A server transceiver with Sync-to-Channel
enabled must have its Sync Channel set to another server’s RF Channel number. A
server with Sync-to-Channel enabled must set its sync channel to a value less than its
RF Channel number. Collocated networks using Sync-to-Channel must use the same
channel set and system ID.
Note: Sync-to-Channel Radio Feature must be enabled.
If server A (with sync-to-channel enabled) can’t sync to server B (on the sync channel),
server A will be unable to communicate with its clients. It must wait until it syncs with
server B (at which point In_Range is asserted), before establishing communications.
Server B will not be affected and can communicate with its clients.
See Appendix I: API for further details and sample configuration.
Max Power
Max Power provides a means for controlling the RF output power of the AC4490.
Output power and current consumption can vary by as much as ±10% per
transceiver for a particular Max Power setting. Contact Laird for assistance in
adjusting Max Power.
Note: The max power is set during Production and may vary slightly from one
transceiver to another. The max power can be set as low as desired but
should not be set higher than the original factory setting. A backup of the
original power setting is stored in EEPROM address 0x8E.
Output Power
Table 6: AC4490-200
EEPROM Value (Hex)
Current (mA)
dBm
mW
0
61
-22
0.01
1
64
-9
0.13
2
65
-3
0.5
3
66
1
1.26
4
67.5
4
2.51
5
70
7
5.01
6
73
9
7.94
7
77
10.5
11.22
8
83
12
15.85
9
88
13.5
22.39
A
93.5
14.5
28.18
B
99
15.5
35.48
C
105
16.5
44.67
D
110.5
17
50.12
E
114.5
17.5
56.23
F
117.5
18.5
70.79
1E
126
19.5
89.13
60
127.5
20
100
Table 7: AC4490-1000
EEPROM Value (Hex)
Current (mA)
dBm
mW
0
430
-1
0.79
1
430
9
7.94
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2
470
14
25.12
3
520
16.5
44.67
4
560
19
79.43
5
650
20.5
112.2
6
740
22
158.49
7
780
23
199.53
8
870
24.5
281.84
9
950
25
316.23
A
1000
26
398.11
B
1080
26.5
446.68
C
1130
27
501.19
D
1170
27.5
562.34
E
1260
28
630.96
F
1300
28
743
System ID
A number from 0 to 256 that provides added security to each independent network
of AC4490 units. The System ID is used in conjunction with the Channel Number and
serves as an RF password to maintain secure transfers of data. The combination of
the Channel Number and System ID must be unique to each network of AC4490s to
establish communication. Multiple servers in the same coverage area must be
programmed with different Channel Numbers to prevent inoperability of the
networks. The System ID will not prevent inoperability that occurs from locating
multiple servers with the same Channel Number in the same coverage area.
Note: Separate Collocated AC4490 networks must operate on different Channel
Networks. All units in a given AC4490 network must have identical Channel
Numbers and System IDs.
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APPENDIX I: API
The API feature set of the AC4490 provides powerful, dynamic packet routing capabilities to the OEM host.
The number of API configurations is endless since individual radios can all be configured differently to suit the
OEM host’s varying needs. Two of the most common implementations are described in the following pages.
Polling Network
Many applications require multiple locations to report back to a single access point. One solution is to enter
Command mode, change the transceiver’s destination address and then exit Command mode to resume
normal operation. When it is time to communicate with another transceiver, the process is repeated.
However, this method costs time and reduction in throughput since unnecessary commands are issued. As an
alternative, the Transmit API command can be used to control packet routing on a packet-by-packet basis.
Figure 3: Polling network
The simplest implementation consists of a smart Shared Access Point (SAP) with a microcontroller or
processor that has Transmit API enabled. The SAP controls which transceiver(s) each packet is routed to.
Broadcast packets should be used when all remotes are to receive the same message. Addressed packets
should be used when communication with a single remote only is desired. An example of each is shown in
the following sections.
Addressed Transmit API
To poll radio 1, the SAP transmits the packet using the following format:
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To poll radio 2, the SAP transmits the packet using the following format:
To poll radio 2, the SAP transmits the packet using the following format:
This continues until the SAP successfully polls all radios.
Broadcast Transmit API
To send out a universal poll request or data packet, the OEM may wish to utilize the broadcast portion of the
Transmit API command. The Broadcast command is similar to the addressed command. However, you must
set all three Destination MAC Address values to 0xFF.
The remote response is dependent on the OEM’s specific needs and equipment. In many cases, remote radios
are connected to dummy terminals without the intelligence to filter out or append specific portions of a
packet that is transmitted or received. Since the seven bytes of overhead in the Transmit API command are
not sent over the RF, the remotes receive only the payload data, STATUS. If auto-destination is enabled on
the remote radio, the transceiver automatically changes its destination address to that of the radio from
which it last received a packet. When the remote device sends its response, it is automatically routed back to
the SAP.
Depending on the API configuration of the SAP, the packet will be received in one of two formats:
Receive API
Time Division Multiple Access Network
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Receive API
When Receive API is enabled, the transceiver receives the reply data and the MAC address of the source radio.
When Receive API is enabled, every packet received by the transceiver is sent to the host in the following
format:
Enhanced Receive API
When Enhanced Receive API is enabled, the transceiver receives the reply data plus the MAC address of the
source radio and one RSSI value (RSSI* is how strong the local transceiver hears the remote transceiver).
It may be useful to the OEM Host to determine from which radio each packet originated. When Enhanced
Receive API is enabled, every packet received by the transceiver is received in the above format.
Normal Receive Mode (non-API)
If Receive API is not enabled, the transceiver receives the reply data only (i.e. “ALLGOOD”) from each
transceiver. With this receive mode, the SAP will not know which radio the data was received from and the
messages will have random receipt times depending on which radio was able to control the bandwidth first.
Loopback Repeater
The simplest repeater to implement is a loopback repeater. A loopback repeater can be created by
connecting the transceiver’s RXD and TXD lines together. When the radio receives data, it will retransmit the
data to all available transceivers on the network. It is important not to have two loopback repeaters in range
of each other as they will continuously transmit data back and forth.
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Figure 4: Loopback Repeater
If radios B & C in the above picture are not within range of radio A, they will not be able to receive or
respond to communications from radio A. A loopback repeater can be added between the three such that it
is in range of both radio A and radios B & C. When the repeater receives a packet from radio A, it will
transmit the packet out to radios B& C. If the repeater is set to Broadcast mode, radio A will receive a copy of
each packet that it sends. If the repeater has a specific destination address (i.e. 12 34 A2), then radio A will
not receive the packet as its MAC address will not match the specified destination address.
Time Division Multiple Access Network
For a more intelligent network, a Time Division Multiple Access Network (TDMA) system can be implemented.
In this system various radios transmit data to a SAP during an assigned time interval. The system is
synchronous so that only one radio is transmitting at a time and has full access to the SAP’s bandwidth. In a
TDMA network, each radio must store its data for the amount of time between its transmissions or bursts. A
typical format for data passing through a SAP is shown in Figure 5. A frame consists of arriving bursts from
remote radios and each frame is then divided into multiple time slots. The bursts can be of varying lengths
and can be longer for heavy-traffic stations. To prevent overlaps, guard intervals can be inserted to absorb
small timing errors in burst arrivals.
Figure 5: Quad Intervals
Example:
SAP sends broadcast packet which includes a sync pulse
Remote radios hear the sync pulse and join the session
Radio A transmits during time interval t = 1
Radio B transmits during time interval t = 2
Radio N transmits during time interval t = N – 1
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This type of implementation requires careful planning and should allow enough time for retries if necessary.
When full duplex is enabled, the radio which initiated the session (SAP) will transmit during the even
numbered hops and the remote radios will transmit only during odd numbered hops.
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APPENDIX II: SYNC-TO-CHANNEL
Note: Information furnished by Laird in this specification is believed to be accurate. Devices sold by Laird
are covered by the warranty and patent indemnification provisions appearing in its Terms of Sale
only. Laird makes no warranty, express, statutory, and implied or by description, regarding the
information set forth herein. Laird reserves the right to change specifications at any time and
without notice. Laird products are intended for use in normal commercial applications.
Applications requiring extended temperature range or unusual environmental requirements such as
military, medical life-support or life-sustaining equipment are specifically not recommended
without additional testing for such application.
Note: For a period of one (1) year from the date of purchase, Laird warrants the transceiver against
defects in materials and workmanship. Laird will not honor this warranty (and this warranty will be
automatically void) if there has been any: (1) Tampering, signs of tampering, or opening the
transceiver’s case. (2) Use of AC power adapters and cables other than those originally supplied
with the transceivers. (3) Repair or attempt to repair by anyone other than a Laird authorized
technician. This warranty does not cover and Laird will not be liable for, any damage or failure
caused by misuse, abuse, acts of God, accidents, electrical irregularity, or other causes beyond
Laird control, or claim by other than the original purchaser.
Sync to Channel - What is it and do I need to use it?
Laird uses frequency hopping protocol with a fixed pseudo-random hopping sequence on our transceivers.
This protocol yields superior interference rejection and multipath immunity. The server sends timing beacons
on a regular interval and clients hear these beacons and synchronize their hopping to the server.
Though servers cannot send packets to each other, they can hear the timing beacons sent out by other
servers. Normally, the servers ignore these beacons. However, when Sync to Channel is enabled, and a
specific server is designated as the synchronization master, the other servers will listen for the beacons from
the master server and then synchronize their hop timing to that server.
Why is this important? If two servers (and their clients) are operating in the same area and their frequency
hopping is not synchronized to each other it’s possible that they might try to occupy the same frequency at
the same time. In severe cases, they could interfere on every frequency, causing very slow communications.
To avoid this kind of interference, collocated servers can use Sync to Channel. Sync to Channel synchronizes
frequency hop timing between these servers so that they never occupy the same frequency simultaneously.
To use Sync to Channel, you should select one server (preferably the most centrally located server) to be the
“Hop Master.” This server should be programmed to a numerically low RF Channel Number and should have
Sync-to-Channel disabled. All other servers in the area should have Sync to Channel enabled and have their
Sync-Channel set to the RF Channel Number of the server chosen as the Hop Master. Preferably, if a server is
outside of the range of the Hop Master Server it can have its Sync Channel set to the RF Channel Number of
another server (with a lower RF Channel Number than its own) that is in range of, and synchronized to, the
Hop Master server.
The following rules apply to Sync-to-Channel:
1. One server should perform the function of Hop Master.
2. The Hop Master server should have its RF Channel Number set to a numerically low value and should
have Sync to Channel disabled.
3. It is preferable that the Hop Master Server be centrally located.
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4. All other Servers in the collocated system (servers that are being synchronized to the Hop Master server)
should have Sync to Channel enabled.
5. All other servers in the collocated system should have their Sync Channel set to a value lower than their
RF Channel Number.
6. All servers, including the Hop Master server, should have their RF Channel Numbers separated by a
minimum of 4-5 Channels (i.e. Server 1, Hop Master = RF Ch 16, Server 2 = RF Ch 21, Server 3 = RF Ch
26…) to avoid inter-channel interference between the radios as they hop through their pseudo-
random hopping sequence.
7. If the servers to be synchronized are in range of the Hop Master server, it is preferable that their Sync
Channel be set to the RF Channel Number of the Hop Master server.
8. If some of the servers to be synchronized are outside of the range of the Hop Master server, their Sync
Channel should be set to the RF Channel Number of a server (with a lower RF Channel Number than its
own) that is in range of, and synchronized to, the Hop Master server.
All collocated servers must be programmed to the same channel set. There are 32 available channels for the
CL4490-1000, as shown in Table 8.
Table 8: RF Channels for AC4490
Channel Set
RF Channel
Number Range
(0x40)
Frequency Details & Regulatory
Requirements
Countries
0 (AC4490 - 1x1
AC4490 - 200)
0x00 - 0x0F
902 - 915 MHz (26 hop bins)
US / Canada
1 (AC4490 - 1x1
AC4490-200
AC4490 - 1000)
0x10 - 0x2F
902 - 928 MHz (50 hop bins)
US / Canada
2 (AC4490 - 1x1
AC4490 – 200
AC4490 - 1000)
0x30 - 0x37
915 - 928 MHz (22 hop bins)
Australia (-1x1/-200/-1000)
What happens if you don’t enable Sync to Channel and you have collocated servers? There are good odds
that you will see a decrease in throughput due to the systems trying to occupy the same frequency at the
same time. In severe cases, you could lose communications all together depending on how much bandwidth
your system requires. Due to crystal differences between the servers, you may see intermittent interference.
Figure 6: Two servers without Sync to Channel enabled
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Figure 7: Two servers with Sync to Channel enabled
How do I configure Sync to Channel?
To configure Sync to Channel, you must use our OEM configuration software. To download the utility, visit
www.lairdtech.com/ramp and click the Product Information tab. Underneath the Software Downloads
heading, click the Laird Configuration Utility. Download and run the installer file.
You will be prompted to install the software on your PC. Once the install is completed, you can open the
software from Start -> All Programs -> Laird Technologies Wireless -> Laird Technologies Config.exe.
Note: Items 2-6 in the following list correlate to the numbered items in Figure 8.
1. The software will open on the Configure tab and you will need to change to the PC Settings tab at the
top of the window.
Note: RF Options mentioned in this procedure require that the “Show All Options box is selected in
the Security Pane on the PC Settings tab of the Configuration Utility. To enable the Security
Pane, see the
Enabling the Security Pane in the Laird Configuration Utility
accessible from the
AC4490 product page (Documentation tab) on the Laird website:
http://www.lairdtech.com/products/ac4490
2. Select the appropriate product from the Product drop-down menu (AC4490).
3. Select the COM Port that your radio is connected to. If you are unsure, press the Find Ports button and
the drop down list will be updated with available COM ports.
4. Select the baud rate that matches the baud rate that the radio is programmed to (the default baud rate
for the 4490 family is 57600.
5. Verify that the COM Port selected is OPEN and that CTS Port 1 is LOW.
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Figure 8: PC Settings tab
6. Go to the Configure tab and click the Read Radio button at the bottom right of the screen. A message
stating “Read Successful” should appear after a successful read (Figure 9).
2
2
6
2
6
2
5
2
3
2
4
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Figure 9: Configure tab - Read Successful
7. To configure the Hop Master, change the Mode to Server and select Broadcast Mode. Make note of
the RF Channel Number. Once the appropriate changes have been made, press the Write Radio button.
A Write Successful prompt will appear after a successful write. Note that the values are shown using
hexadecimal representation; this can be changed to decimal notation by double-clicking on the word
“Hex” (it will change to “Dec”).
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Figure 10: Hop Master settings
8. Configure all clients that will communicate with the Hop Master Server as clients in Auto Destination
and with the same RF Channel Number as the Hop Master Server (Figure 11), and then press the Write
Radio button.
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Figure 11: Client settings
9. Set Server #2 as a server in Broadcast Mode with an RF Channel Number at least 4-5 steps above the
RF Channel Number of the Hop Master. Under the Radio Features section, select the Sync to Channel
box and in the Radio RF section, set the Sync to Channel to the RF channel of the Hop Master (Figure
12). Press the Write Radio button to write the changes to the radios EEPROM.
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Figure 12: Server #2 settings
10. Configure the clients that will communicate with Server #2 as Clients in Auto Destination and with the
same RF Channel Number as Server #2 (Figure 13). Press the Write Radio to write the changes to the
radios EEPROM.
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Figure 13: Client settings
11. Repeat step 10 for each server that needs to synchronize to the Hop Master; if the server will not be in
range of the Hop Master Server, set its Sync to Channel to the RF Channel Number of another
synchronized Server that is in range of the Hop Master (make sure the RF Channel Number of the
server is higher than the Sync to Channel).
12. Repeat step 11 for all clients that will communicate with each server.
I’ve configured my radios, what’s next?
Once you have configured all radios, your network should be set up similar to the one shown in Figure 14.
The main server or hop master must be powered on anytime that the other servers are connected to enable
them to synchronize and communicate with their clients. If a centralized network does not work and all
servers are not in range of the hop master, a daisy chain network can be used as shown in Figure 15.
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RELATED DOCUMENTS AND FILES
The following additional AC4490 technical documents are available from the AC4490 product page
(Documentation and Datasheet tabs) located on the Laird website:
http://www.lairdtech.com/products/ac4490
Product Brief
AC4490 Hardware Integration Guide
Statement of Compliance to EU WEEE Directive and RoHS Directive
The following downloads are also available from the RAMP Product Information tab:
Laird Configuration Utility
USB Drivers
AC4490 RF Diagnostic Suite
AC4490 User Guide
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Laird Technologies is the world leader in the design and manufacture of customized, performance-critical
products for wireless and other advanced electronics applications. Laird Technologies partners with its
customers to find solutions for applications in various industries such as:
Network Equipment
Telecommunications
Data Communications
Automotive Electronics
Computers
Aerospace
Military
Medical Equipment
Consumer Electronics
Laird Technologies offers its customers unique product solutions, dedication to research and development, as
well as a seamless network of manufacturing and customer support facilities across the globe.
Copyright © 2013 Laird Technologies, Inc. All rights reserved. The information contained in this manual and the accompanying software programs are copyrighted and all rights
are reserved by Laird Technologies, Inc. Laird Technologies, Inc. reserves the right to make periodic modifications of this product without obligation to notify any person or entity
of such revision. Copying, duplicating, selling, or otherwise distributing any part of this product or accompanying documentation/software without the prior consent of an
authorized representative of Laird Technologies, Inc. is strictly prohibited.
All brands and product names in this publication are registered trademarks or trademarks of their respective holders.
This material is preliminary. Information furnished by Laird Technologies in this specification is believed to be accurate. Devices sold by Laird Technologies are covered by the
warranty and patent indemnification provisions appearing in its Terms of Sale only. Laird Technologies makes no warranty, express, statutory, and implied or by description,
regarding the information set forth herein. Laird Technologies reserves the right to change specifications at any time and without notice. Laird Technologies’ products are
intended for use in normal commercial and industrial applications. Applications requiring unusual environmental requirements such as military, medical life-support or life-
sustaining equipment are specifically not recommended without additional testing for such application.
Limited Warranty, Disclaimer, Limitation of Liability
