Monday, September 16, 2019

Flirc 1 button

Power button for the Raspberry Pi

Created a custom top plate for the Flirc 3B case. The original top was made of black plastic and had little tabs that snapped into cut outs in the top of the aluminum case. The top I made is just a flat piece of PCB material with black soldermask. The PCB has a 14mm square hole to fit a Cherry MX style switch.

I use 3M VHB tape to hold it in place. The VHB tape is 0.8mm thick. This creates a gap between the case and plate that the thin 30AWG wire can fit through. The wires pass through one of the cutouts to the Raspberry PI GPIO pins inside the case.

The PCB is about 1mm smaller then the recessed area. I manually centered it, 0.5mm gap on each edge. This also fits the Flirc Pi 4B case, except that the recessed area is larger and there is a larger gap on the top/bottom edges.

I used small pieces of the 3M tape. It is very strong and would be difficult to remove if needed. Thin kapton tape is used to keep the wires from moving around.

A 2x3x4mm size LED fits inside the Gateron clear top switches. Zealio switches have the same design.

A current limiting resistor connects the cathode of the LED to one of the switch pins. This shares the ground connection back to the GPIO header (black wire). The anode of the LED is connected to the red wire which connects to GPIO4. The other pin of the switch is connected to GPIO3 with the blue wire.

The wires pass though one of the cutouts and I used a wirewrap tool to connect them to the GPIO pins.

Another angle view of the connection to the GPIO pins. Ground. GPIO3 used for the power switch. GPIO4 used for the activity LED.

Info on the power button and how to set it up can be found here:

Info on the activity LED here:

Gerber files on git. The board is less than 100mm square, and can be manufactured at a discount at many PCB fabrication houses.

Video of the activity LED. This is starting from a shutdown state. Shorting GPIO3 to ground will restart the Raspberry from this state. The activity LED is using the CPU trigger. There is a short delay on startup and before complete shutdown where the Raspberry Pi's original activity LED is in use instead of the GPIO LED.