(XPB24 with firmware 1084)
Everything started well. Using the development kit, I was able to successfully run the loopback test.
I wanted to start very simply with two units in transparent mode. I changed the data in both units using X-CTU and logged out and back in to verify they had been changed. The data changed was minimal:
- Changed baud rate to 38,400. Verified simply by the fact that I could not talk to the units from my PC until I changed the baud rate to 38,400.
- Removed all flow control since I am only planning on using 5% of the link
- Made sure that the Channel and PAN ID were the same in each unit.
- Changed the Destination address so each unit has the 64 bit address of the opposite unit.
I am only connecting 4 wires to the units, Power, Gnd, Din , Dout.
I power one up and send 5 bytes of data to Din repeatedly (~5% duty cycle). My scope tells me that I am sending Start, 8 bits of data, and stop (NRZ). Nothing comes out the other end of the “virtual wire”.
If you don’t use all of the advanced networking capabilities, there doesn’t appear to be much that needs to be configured. What am I missing?
It would be nice to have a set of simple examples documented.
Update:
Power conditioning was to blame. I had a 10 uf cap right at the input but I guess that wasn’t enough. I had to add a 2200 uf electrolytic in parallel and then everything started working.
I had posted a question as to minimum configuration to run an XBee module and didn’t hear anything back. I think, technically, you are correct in being able to run with the 4-wire connection (power, ground, data in, and data out). I have set up a fairly minimum system using the coordinator and three routers. The three routers all have the coordinator as their destination addresses (ATDH0 and ATDL0). I’m having each router node send about 25 bytes every second. I’ve set up the serial interfaces all around to 38400,N,8,1. When I start the coordinator and the first router node, everything works fine. I see the input data and save it off to a disk file. When I start the second router node, it also works fine. The data at the coordinator is the interlaced sum of both router nodes. When I start the third router node, though, it locks up the coordinator node. The amount of time to send the 25 bytes should be (1/38400)seconds/bit * 10 bits/byte * 25 bytes = ~6.5ms. The total duty cycle for all three nodes should be (3 * 6.5ms) in 1 second or about 1.95% for the sum of all three nodes. I think the problem may be related to having data queued in the transmit buffer but the radio doesn’t send it out because the coordinator is receiving data from another node or the router node has not established a path to the coordinator yet. I am hoping a simple examination of the CTS pin will indicate when it is OK to send a message from the router to the coordinator.
This is just an FYI. If this doesn’t apply to your system, please disregard.
Dave