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©2010-2011 by RF Monolithics , Inc. E-mail: tech_sup@rfm.c om XDM2510H - 03/17/11
Mode 1 Pin Usage
Pin I/O Usage
UART_RX Input Serial data moving from the microcontroller to the XDM2510H.
UART_TX Output Serial data moving fro m the XDM 2510H to the microcontroller.
/MT_RTS Output
/MT_RTS provides a mechanism to wake the microcontroller in order to receive a packet. /MT_RTS is asserted
when the XDM2510H is ready to send a serial packet. The signal stays low until the /SP_CTS signal from the
microcontroller is detected low by the XDM2510H, indicating readiness to receive a packet, or the tMT_ R TS to
SP_CTS timeout defined in Section 8.4.3 expires. If /MT_RTS times out, it will de-assert /MT_RTS, wait for tMT_RTS
retry and then re-asser t /MT_RT S to attempt to send the pa cket again. / MT_RT S may be ignored by the micro-
controller only if /SP_CTS always stays low.
/SP_CTS Input / SP_ C T S prov ides packet level flow control for pac ke ts tran s ferre d from t he XD M2 510H to the microcontro ller.
When the microcontroller is capable of receiving a packet it should assert the /SP_CTS signal. /SP_CTS may
be externally tied low (reducing pin count) only if the microcontroller is always ready to receive a serial packet.
/MT_CTS Output
/MT_CT S provides packet level flow control for packe ts trans ferre d fro m t he mi cro co ntr oller to the XD M2 510H
that are destined for transfer over the network . Upon reset, following boot the XDM2510H will negate /MT_CTS
until the XDM2510H establishes a wireless network connection. During operation, the XDM2510H will negate
/MT_CTS if the XDM2510H does not have sufficient buffering to accept another packet. /MT_CST will als o
remain high if the XDM2510H is not part of the network. The microcontroller must check that the /MT_CTS pin
is low before initiating eac h seri al packet for w ireless tran s missi on. Note that the XDM2 510H may receive
local serial packet s at any ti me rega rdless of the /MT_CT S s tate.
/TIME Input The /TIME pin can be use d for trigg ering a timestamp packet. Its usage is optional.
Table 15
8.4.2 Mode 3 - Five Signal Serial Interface (9600 b/s)
The XDM2510H Mode 3 provides a five-signal serial interface with byte-level flow control on transfers from the
XDM2510H to the microcontroller. The Mode 3 serial interface is consists of data pins UART_TX and UART_RX,
with handshake pins /MT_RTS, /MT_CTS and /SP_CTS used for bidirectional flow control. The /MT_RTS signal
is ideal for designs where the microcontroller requires extra time to prepare to receive a packet. For example, the
host microcontroller sleeps periodically and requires a wake-up signal prior to receiving a packet). Refer to Table
16 for information on each handshake pin, including details on which of those pins are optional.
Mode 3 Pin Usage
Pin I/O Usage
UART_RX Input Serial data moving from the microcontroller to the XDM2510H.
UART_TX Outp ut Serial data mo ving fro m the XDM 2510H to the microcontroller.
/MT_RTS Output
/MT_RTS provides a mechanism to wake the microcontroller in order to receive a packet. /MT_RTS is as-
serted when the XDM2510H is ready to send a serial packet. The signal stays low until the /SP_CTS signal
from the microcontroller is detected low by the XDM2510H indicating readiness to receive a packet, or the
tMT_R TS to SP_CTS timeout defined in Section 8.4.3 expires. If /MT_RTS times out, it will de-assert /MT_RTS, wait
for tMT_RTS retry and then re-assert /MT_RTS to attempt to send the packet again.
/SP_CTS Input
/SP_CTS pro vide s bo th pa cket level and byte level flow control for packets transferred from the XDM2510H to
the microcontroller. When the microcontroller is capable of receiving a packet it should assert the /SP_CTS
signal. In Mode 3, byte-level flow c ontrol is achieved by having the microcontroller de-assert and then re-assert
the /SP_CTS signal following the receipt of each byte. The XDM2510H will begin transmission of the next byte
after detecting the re-assertion of /SP_CTS.
/MT_CTS Output
/MT_CTS pro vide s pac ket leve l flow control for packets tran s ferre d fro m t he mi cro co ntr oller to the XDM2510H
that are destined for transfer over the network . Upon reset, following boot the XDM2510H will negate
/MT_CTS until the XDM2510H establishes a wireless network connection. During operation, the XDM2510H
will negate /MT_CTS if the XDM2510H does not have sufficient buffering to accept another packet. /MT_CTS
will also remain high if the XDM2510H is not part of the network. The microcontroller must check that the
/MT_CTS pin is low before initiating each serial packet for wireless trans mi s sion . Note tha t the XDM2 510H
may receive local serial packets at any time regardless of the /MT_CTS state.
/TIME Inpu t The /TIME pin can be use d for trigg ering a timestamp pac ket. Its usage is optional.
Table 16