Hi,

I am observing a strange error in my transmit and receive code. The problem manifests itself as follows.

I have configured one module to send a simple message upon activating an external interrupt (i.e. a simple pushbutton switch). The message is a broadcast message and consists of a few bytes. Once the message is transmitted and the pushbutton is released, the module goes to sleep (not deep sleep). This node is configured as an end device.

Another waspmote is configured to receive these messages and to toggle a few digital I/O in response. This node is configured as the coordinator and never goes to sleep.

The above combination works well for a while. When I leave the system in idle for a while (for abour few minutes) and press the pushbutton again, it wakes up and tries to send the message as expected (I can clearly see this on the terminal as debug messages). However, this time transmit errors are reported by the API. When I press the button for a few more times, the transmitter magically seems to recover and starts to operate exactly as intended. This error is reproducable by the way.

I sometimes get the same error upon waspmote power up. It looks like the XBee module is busy doing something at start up (or after a long pause) which blocks the transmission of messages (maybe due to something like channel scanning that kicks in automatically etc.). I also suspect such behaviour may be due to the internal settings of the XBee modules (as set by the XCTU). Maybe one of the default settings needs to change but I am not sure which one. I am not very familiar with the internal workings of the XBee module yet and therefore I cannot pindown the source of this behaviour.

Does anybody have an idea on what is going on here? Any feedback will be greatly appreciated.

Regards...

Hi,

Maybe it is due to a setup time which the XBee modules need before sending messages. If you switch the module on after being off, you'll find out some delay until it works ok. How much time are we talking about? Try not to switch off the XBee module and see if there is any difference.
This time is longer for XBee-ZB than other XBee modules. ZB needs more setup time than 802, Digimesh, etc.

Best regards

I am not sure whether is is due to the XBee setup time. Before I can successfully transmit 4-6 seconds is needed after a TX error has occurred. By the way, I do not turn the XBee module off at all.

I have performed another test to get a better understanding of this problem. I swapped my end device with a router and repeated the same tests on the same waspmote. This time the TX errors magically disappeared. This may indicate a few things:

1 - The XBee module that was configured as an end device has hardware/firmware problems.
2 - The End device may be automatically going to deep sleep/hibernation after an internal timeout regardless of the API.
3 - The XCTU configuration settings of the end device are not all accurate.

Hi,

I am thinking in the second idea as the more likely. End devices are the only type of XBee-ZB which go to sleep. You should study how the sleep cycles are controlled. Routers and coordinators never sleep. Keep me up-to-date.

Best regards