Xbee power-on or start-up problem

I’m using a bare SMT Xbee 3 as a basic transparent wireless serial link running in 802.15.45 mode. It’s driven from a Pi Pico.

It successfully works while powered (via Pico USB cable). However upon applying external power to the Pico, the Xbee fails to communicate with it’s remote “mate” (both configured successfully in XCTU). By momentarily removing and restoring the Xbee 3.3V it immediately works as normal.

Thus I think it’s not powering up in a stable manner. I’ve tried delays in the code, setting the TX pin low or high for a period directly after power up - no luck. Wires are pretty short although I am still in breadboard. Voltage is good 3.3V.

I’ve used these before, but with a custom PCB (making serial dongles pairs). Any clues out there? Xbee-3 24DMRM

cheers John

I wold suggest looking at the slew rate or ramp up rate on the battery source. It probably is causing the radio to not power up all the way.