How to use UART with battery powered Wio-E5 mini

Hi there,

I have a Wio-E5 mini. I am able to communicate with the device using AT commands to pins PB6 and PB7 with the factory AT firmware if the device is powered by USB connected to my computer.

If I use a 3.7v lipo battery to power the Wio-E5 however the device is unresponsive to AT commands (it just seems to echo them back?)

Is there something specific I need to do to use UART with the Wio-E5 when on battery power?

There seems to have potentially been someone with the same issue here: Wio-E5 mini connect via UART PB6/PB7

Thank you!

According to the schematic, PB6 and PB7 communicate with USB via USB_Serial bridge.
Where are the AT commands given when power is supplied from battery?

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Thanks for the response @msfujino

I am sending basic commands from my Raspi Pico to Wio-E5 like AT\n and AT+MODE=TEST\n.

The commands work when the Wio is powered via USB, however when it is powered by battery they stop working.

Also do you have a link to the schematic you’re referring to so I can ensure I’m viewing the same document? I have this one - - but want to make sure we’re on the same one.


I am looking at the same schematic as you.
The CP2102 is powered only from USB 5V, not from the battery. PB6 and PB7 are connected to Pico, but also to pins 20 and 21 of CP2102, which are not powered, via 20 ohms, which may cause signal problems.
What do you think if remove R3 and R4, the problem will go away?

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Thanks for the detailed response! I’m not a native electronics engineer (software mostly), so am having to decipher some of the terminology here as I go along.

To be clear - given what you’ve said, is it possible to have a UART (or perhaps USART or LPUART) connection between Pico and E5 with the E5 factory AT firmware and battery power only? Or do I have to write my own firmware?

Looking forward to being able to solve this problem! :slight_smile:

I am using Wio-E5 mini and unfortunately I cannot check your problem because I have already rewritten the firmware.

The easiest way is to change to Grove-LoRa-E5 without CP2102 implemented and send AT commands from Pico.
Also, if you use Wio-E5 mini, you can rewrite the firmware to run the sketch without Pico.
Please refer to some links below.
Node using XIAO_nRF52840 and Grove-LoRa-E5 running on AT commands, sleep current 6.4uA

Programming LoRa-E5 with Arduino, LoRa-E5 mini Point to Point Comminucation over 10 km

Thanks again for the response.

I also have another Wio-e5 dev board which has UART grove connectors. I’ll take a look at the schematic for the dev board to see if it can do UART over battery/grove power?

And I will probably have to write my own firmware for the board, but in the meantime am hoping I can make a POC with the AT command program.

update: I have switched to the Wio-E5 dev kit and am using the USB->TTL pins. This permits sending and receiving UART from an external device when the E5 is powered by battery.

I am still interested in finding a solution for the E5 mini however and will update this thread if I find one.