TTL/CMOS levels on XBee RF Interface Module

Rabbit
1

Hello,

Has anyone successfully connected the XBee RF Interface Module to their RCM using the TTL/CMOS connections? I’m currently attempting to interface the XBee module from my ZigBee App Kit with my RCM3200 using the RCM31xx/32xx prototype board on Serial Port D. The prototype board provides Serial Ports B and C at RS232 levels, but D is only available directly on PC0, PC1. Ports E and F would also be available in similar fashion, if I understand correctly. I will eventually need ports E and F at RS232 levels, so I plan to add a MAX233 chip for those ports, but if I can, I’d like to simply interface Serial Port D directly to the XBee module, without the need for an extra transceiver.

I have succesfully tested the XBee module on Serial Port B using the standard serial port header provided on the board, but when I remove the “Enable RS232” jumper on the XBee interface module and connect the appropriate J4 signals to PC0, PC1, the application fails to find the XBee modem.

I believe I am correctly changing the serial port macros, and I’m pretty confident in the hardware setup, so mostly I’d like to know if anyone has any potential gotchas here that I’ve overlooked.

Also, if anyone can point me in the direction of good info on interfacing Serial Ports E and F to a MAX233 transceiver (or similar), I would greatly appreciate it. I’d like info both and hardware and software, but especially any info on specific Dynamic C methods for enabling these Serial Ports as Asynchronous, etc.

Thanks,
Jon

2

Jon,
As far as I know there are no issues with interfacing the Rabbit to the RF Module Interface board through the TTL J4 header.

I attached a sample program that I created to test the J4 interface. This sample was used with the RCM33xx development board, which is similar to the RCM31xx/32xx board. It also uses serial port D. Make sure you disable the RS232 transiever when using the J4 interface.

3

Thanks so much for the reply! Once the attachment is approved, I’ll give that code a shot and let you know.

Thanks again,
Jon

4

Thanks again for the sample code! I was able to get it working – I just had to disable flow control, as I don’t have those lines connected. Is there a good reason why I should connect those lines and enable flow control? Or am I OK leaving it as is?

Thanks again,
Jon

5

Jon,
See section 2.1.4 in the XBee manual, there is a good explination of how flow control works:

http://www.maxstream.net/products/xbee/manual_xb_oem-rf-modules_802.15.4.pdf

Tony