Raspberry Pi (RPi) - Adding a Reset Switch

 

 

 

 

 

 

As I am playing around with a number of Raspberry Pis and getting more and more enthusiastic about them, I was wondering if thereīs not a better option to reset them, other than pulling the power cord every time.
I found this article how to add the jumper pins to the RPi board, but did not find that smart enough, as it would need you to push a button manually. I just thought of a more flexibel and smarter option.

 

By adding a standard MOSFet Transistor instead of a jumper, we create an electronic switch, which acts on a high-level at its gate. So in principle we could tell the RPi to reset itself by connecting the gate of the BS170 transistor to one of the GPIO pins (I have not tested this yet, as this requires the GPIO ports to be initialized properly and not to have a high level during boot process)

 

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Here you can see the modified PCB. The upper hole of the reset jumper pins is ground, the lower one the reset line. The orientation of the transistor should be clear from the picture. The middle leg of the BS170 is the gate. To supress any distortion probably received by the gate, I soldered a smd resistor of 33kOhm between the gate and ground. This canīt be seen on the pic, as itīs underneath the transistor, right between the legs.
When you touch pin 1 of connector P1 with the blue wire (this is 3,3V)the transistor gets conducting and initiates the reset.

Not very spectecular, but I guess quite efficient!

Have fun!
BR
Ralf