xbee interface not working

[danjel]

I have a prototype pcb made for the following circuit:

Can anyone see a reason why my xbee is unable to communicate?? When I wire the tx and rx points directly with wire I have no problem with transmissions. As soon as I use just the xbees (and a pair that are known to work with other devices) I get no reception or transmission.

**broken link removed**

 

[danjel]

Just to follow up:

I have made sure that I am getting 3.3V at pin 1 of the xbee. Also I only have Jp5 in place so that the max481 chip is disconnected from the tx/rx lines.

I have made a simmilar pcb before (using the same xbee pins: pwr, gnd, din and dout) so I am totally baffled as to why this is not working.

$20 reward to whoever figures this out!!

 

[Mr RB]

I think you should tie the reset and other pins of the XBEE to the correct levels to make it operate.

It's possible the PCB is allowing noise to trigger those inputs and give faulty operation, but when it was wired (no PCB) you might have been getting away with it.

The XBEE datasheet should have info on how to tie the pins, ie what needs to be grounded etc, and it might even have some PCB design info, or maybe that is in another datasheet I can't remember.

 

[danjel]

I managed to confirm that there is nothing wrong with the firmware/configuration of the xbees.

What I meant by "works when wired" was that when I used the exact same pcb but pulled out the xbee and wired into the xbee socket pins at the tx and rx points.

I have another pcb I made before that used the exact same 4 pins of the xbee (and nothing else) and it works totally fine. I am re-building the circuit on another pcb to see if it was some sort of fault in the build (these are proto pcbs without solder mask so there may have been a short somewhere I did not see).

I have not found a data sheet yet for the xbee with more tips on pcb integration but I will do some more searching...