Reset of module RAK11720

Hello there,

I recently produced a pcb with the RAK11720, but i noticed that the RAK module resets very easy, when i put a screwdriver in the + or - of the input or i disconnect the output the module resets directly and starts again. probably this generates a pulse but i dont know how this can happen. Somebody ever heard about this problem?

ps: i have a reset button connected to GP25 to ground.

Kind regards,

Please elaborate what you do with a screwdriver on a powered up device?

What do you mean with + or - input? Input of what???

What is the output you are mentioning???

The input +/- is the input voltage of 24V, this is regulated to 3.3 with a ldo. when i put a screwdriver in the + or - of the connecting blocks of my pcb the module detects a pulse and reset.

And the output of the module is a digital output (in my pcb : gp37) via a mosfet which is connected to a pump. when i disconnect the pump (connector) the module is also detecting a pulse and resets the module. So the thing is that the module detects a pulse to reset.

So it is a custom PCB with the RAK11720 on it.

Not much I can say without knowing the schematics.

Do you have any protection against ESD or fluctuating power source on your PCB? Do you have enough capacitors on the board to protect the electronic against ripples on the supply voltage.

Is your output in anyway protected against peaks that the pump can generate when switching on or off?
The motor in your pump is a inductive load, that can send back energy into your control mosfet, you have to check what is happening when you switch the pump on/off or disconnect it.
When touching the power input, you might inject ESD pulses or create

Yes its a custom pcb, yeah this could be could the problem, i check this with the scope to see whats happening. I have 2 capacitors on the input of the supply voltage, (before and after the voltage regulator).

I will check this out and let you know.

Thanks for your help!