CubeCell-GPS 6502: issue with UART0 pins when powered from battery

I’ve created an issue report on the CubeCell GitHub page which related to this topic:

It happens to me only when the board is powered from battery. USB power is doing good.

Does anyone have same or similar symptoms ? Any ideas on how to fix it?

There is a known workaround to start both on battery and USB, then disconnect the USB cable. But this works only until I press the RESET button.


Thank you for your feedback, I’m discussing this issue with our colleagues.


We got the result. This was what we designed for low power consumption.
The situation is roughly like this:
When USB is powered, the serial port chip CP2102 will be powered on, and RX1 will be pulled to a high level . When you use this statement “Serial.begin();” in your code, the level of RX1 will be automatically detected. If RX1 is high, the serial port will be opened, so TX1 can The waveform is detected.

When only battery powered, cp2102 is not poweredand RX1 is not powered on either. The serial port is not started, RX1 has no waveform.

One of the solutions: Before the system starts (only battery power supply), the hardware method is to set RX1 to high level.

Thank you for reply and processig of the ticket on GitHub.
I confirm that when I connect both 2 wires (Rx and Tx) of an external adapter to Tx1 and Rx1 pads of the CubeCell - this issue does no longer appear.