A little background info: We are developing a remote home monitoring system with cell phone interface. My group’s advisor told us that another group did it a couple semesters ago, so we inherited their stuff which included a GM862 EVK V3.
I have a Freescale Zigbee development kit (2x 13192-SARD boards) and was going to use one of the SARD boards to send AT commands over Serial to the GM862. The SARD board has a 9S08GT60 microcontroller that would be handling all of this.
The problem: I can send the AT commands from the SARD board to the GM862 just fine, but I never get back a response. Sometimes, it echoes the ‘A’, ‘T’, and ‘\r’, and sometimes it doesn’t. Regardless, I have never seen it respond with “OK”.
They are communicating at 9600 bps. I know that the SARD board is sending the “AT” just fine, because after I send it, I hook up the GM862 to a PC and send “AT#MONI” over hyperterminal and get the right response.
I developed a test app to test the null modem cable and the serial receive interrupt handler between the two SARD boards. One sends “AT” and the other echos the characters and sends “OK”. It all worked just fine. My null modem cable only has the Tx, Rx, and GND lines. Does the GM862 EVK require the rest of the pins?
Also, The GM862 EVK that we inherited appears to have a hardware modification. On the right side of the board, the RXD line is soldered to an unkown test point the the right and below it on the back of the board. Any idea what this might’ve been for?
Thanks for any help!