# Freescale MC9508 secondary processor not talking to EM357 radio

**URL:** <https://forums.digi.com/t/freescale-mc9508-secondary-processor-not-talking-to-em357-radio/19742>\
**Category:** XBee & XBee Gateway\
**Tags:** serial, processor, secondary, xbee\
**Created:** [July 25, 2018, 7:53am UTC](https://forums.digi.com/t/freescale-mc9508-secondary-processor-not-talking-to-em357-radio/19742 "2018-07-25T07:53:07Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![djmauro](https://avatars.discourse-cdn.com/v4/letter/d/bc79bd/32.png) [@djmauro](https://forums.digi.com/u/djmauro)\
**Post date:** [July 25, 2018, 7:53am UTC](https://forums.digi.com/t/freescale-mc9508-secondary-processor-not-talking-to-em357-radio/19742/1 "2018-07-25T07:53:07Z")

</div>

I have an XBee S2CTH (XB24CZ7UIT) module running version 4060 of the zigbee firmware. It is configured as a router. I wrote and compiled an application program in CodeWarrior and uploaded it to the module using the XModem feature in the legacy X-CTU program. It seems to start up ok and output is displaced in the Terminal window.

I setup an API Transmit frame (formulated using the XCTU Frames Generator, so it is a valid packet) and then try to send it from the application to the radio using uart\_write (after initialization: radio\_uart\_config (115200, UART\_CFG\_BITS\_8 | UART\_CFG\_PARITY\_DIS)).

The packet contents are displayed in the Terminal window; however, it seems they are not sent serially to the radio. That is, uart\_write appears to be sending the data out to the host on the external DOUT line instead of the internal DOUT\_Radio line. This is wrong - what am I missing?

Also, the RSSI light lights up at startup when, I presume, the device joins the network. This is confirmed by the output from my xbee\_modem\_status\_handler ISR which is called for this event.

I feel it must be a configuration issue - something fundamental, but the SDK documentation is lean. Any help here much appreciated.  
Thx.