Problems with UART - BG95M3

QuecPython
1

Hi,

We are trying to perform read/write operations on the UART of the BG95-M3, and the strategy we are following is as follows:
We are using UART 0 → Tx = Pin 23. Rx = Pin 22.

baudrate, databits, parity, stopbits, flowctl = 115200, 8, 0, 1, 0

uart0 = UART(UART.UART0, baudrate, databits, parity, stopbits, flowctl)
  • We open the UART with the function uart0.init(baudrate, databits, parity, stopbits, flowctl).
  • We add the callback to the UART.
  • We perform read/write operations.
  • We close the UART with uart0.close().

This process is done every minute, although the time is configurable, ranging from a few seconds to several minutes.

The issue occurs when, after a considerable amount of time (2-3 hours), the initialization line throws the following error:
UART(0) init fail.

I am testing without closing the UART using the uart0.close() instruction, i.e., we keep it open the whole time, and it has been running for a full day without crashing. However, the consumption is much higher, around 12 mA, so we would prefer to use the strategy of opening/closing the UART when needed, with a consumption of around 3/4 mA.

Why is this problem happening?

Is there any limitation on the number of times we can initialize/close the UART process, or could it be related to how Quecpython handles resource release when executing uart0.close()?

2

Hi,

The modem may not enter deep sleep when the UART is open; if the fast power-on/power-off coincides with the sleep transition when closed, EBUSY / UART(0) init failure may occur.

Can you try increasing the power-on/power-off frequency to ≥ 5–10 seconds?

Empty the RX buffer before shutting down.
Add a 50–100 ms delay before shutting down/sleeping.
It would be beneficial to apply a retry/backoff during startup.

3

Hi,

I will try the suggestions.
Thank you very much for the quick response.

BR