I've been using the ATOM RS-485n kit (https://docs.m5stack.com/en/atom/atomic485) to connect to an electricity meter using ESPHome. Last night this was working with the A/B wires connected to the meter and the ATOM lite powered via the USB connection to my laptop.

Today, for some reason, if I plug the ATOM lite into the RS485 unit then it won't power at all via USB whether or not the A/B wires are connected. I must be doing something different, but for the life of me can't work out what is different.

Should I expect to be able to power it by USB? Is there something I might have done (software or hardware) that would stop that happening. The ATOM lite is still working - if I connect it without the RS-485 base then it works exactly as expected.

Any suggestions very welcome!

Andrew