Topics created by nvko23

@felmue said in StamPLC: Replace RTC battery?:

Hello @nvko23 solitaired

after opening my M5StamPLC I found that the RTC battery is located at the underside of the CPU board. It is soldered to the board. So yes, I'd say it is replaceable, but the proper soldering tools are required.

BTW: the RTC battery in my M5StamPLC seems to be completely flat as I measure 0 volts.

Thanks
Felix

Great, thanks you very good

Hello @nvko23

well, according to the schematics, SYS_INT is connected to multiple ICs, including PI4IOE5V6408, RX8130, AW9523, LM75 and INA226.

The required pull-up resistor (5.1k) is R10 - it's drawn near PI4IOE5V6408 on the CPU schematic.

Edit: I ran some tests - this is what I found:

Without any connections to Inputs 1 - 8 SYS_INT is high (as expected). However if any input is asserted while powering up M5StampPLC SYS_INT goes low even though AW9523 interrupts are disabled during its initialization. See here.

Adding _io_expander_b->resetIrq(); in the M5StapPLC library after disabling interrupts changes SYS_INT back to high.

My conclusion: AW9523 by default at power up has interrupts enabled and any interrupt sticks even when interrupts are disabled later on.

Thanks
Felix