I have a pcb board with an msp430 on it. Using the XTCU software and 2 development boards from Digi, I am able to send a character from one xbee to the other, have the micro controller interpret the character via uart, send a response and receive it back on the original xbee. The problem comes when I disconnect the second xbee from the computer usb and power it using the wall adapter. After doing this I no longer receive expected characters back to the Xbee connected to xtcu. Any ideas what could be causing this?? When both Xbees are powered from the computer usb, they work flawlessly…
How are you connecting your MSP to the radio and the board? Is the Loop back jumper connected on the board? How are you powering the XBIB board?
The msp430 is on its own pcb board with a vreg circuit outputting 3.28 volts. Im connecting the tx/rx uart lines from the uC to the Xbee board with just a couple of wires right now. I soldered headers to the xbee dev board to connect the wires to the dout and din lines.the loop back is not connected. Both xbees are on dev boards connected to usb power and both are in AT mode. I changed the code on the uC to send 0x61 or ‘a’ every second to the UART lines which I can see being recieved in the xtcu software on the other xbee. Using the wall power adapter the xbees came with, I connect the xbee board with the microcontroller and disconnect the usb and the stream of 'a’s stops…
I just figured out that connecting the grounds of the xbee dev board and the pcb board with the uC on fixes the original problem. I think it had to do with the voltage levels coming from to and from the xbee din and dout pins.
My next problem is when I plug the Xbee directly into my pcb board it does not work. The pins i have connected are ground, power, din, dout, associate indicator, and sleep. The associate indicator is blinking which, according to the data sheet, means the xbee is properly functioning but I am still not receiving any characters. Am I missing some circuitry? Or possibly the settings with the internal pull-up/down resistors on the xbee? I am still not sure.
I did some further testing. When the xbee module is plugged into my board the dout pin voltage is sitting at 1.6 volts when the module is not receiving anything. The idle dout pin should be at 3.3 volts until data is received and begins its transmission the the microcontroller since 3.3 is the stop bit voltage. Any idea what could be causing this?