Hi,
I am currently designing a Low power consumption LORA board.
The HT-AM02 module will wake up and fall in sleep periodically to transmit data through the RF channel (Period around 6s during testing). It will wake up the ESP32 every 1.5minutes and receive data from and ESP fall to sleep again.
It seems no error during the first few hour testing. So I continue test the board for 2 days. After that 2 out of 4 of the board stop functioning. The battery is not exhausted. And I found that on one of the board, pin 21 is shorted to GND. No matter how I reboot the module and even when the board is not powering, it is measured to connected to the GND directly. And on the other one, it’s reset pin shows the same condition so when I power it, it is in reset state.
I dont think it is the soldering issue since by inspectation , it is definitely not short to any other pins. And they are tested to be function well before the 2days test.
However, after resolder the corresponding pin, they become functionable again. It confused me.
I cant repeat the problem so far.
What could be the possible cause?
Attached part of the schematic. The ESP32 is shared the same power as LORA module. They are communicated through UART (pin 21, 22). Other sensor are powered through mosfet controlled by LORA module.
