Using GPIO hardware status led

Seeing the Phoniebox status (on, off or shutting down) by an led

Note Before we start: Let's remember a Phoniebox rule: Just plug and play using USB, no soldering iron needed. One might to take soldering or GPIO work into account when it is then possible to see the power status of the Phoniebox be an led.

The status LED is supported out of the box. That means it only has to be connected to the Raspberry Pi. The connection is explained below.

Status led features and behavior

• Lighting up when the Phoniebox is fully bootet and ready to respond to card requests
• Reacting on pushed GPIO hardware shutdown button by blinking when shutdown command is accepted
• Going off when the Phoniebox is ready (system has shut down) to be switched off by the main switch (RPi can be disconnected from power supply) so it can be turned off more gracefully.

Connecting the Status led

As mentioned in the flexible hardware layout the status LED has to be connected to GPIO 12 (which is pin 32). Pin numbering and positions on the Raspberry Pi can be found in the description of the GPIO hardware buttons.

This pin is already configured as output in the Phoniebox software. As documented at the Raspberry Pi GPIO documentation this pin outputs 3.3 Volt. So you should pick an led based on that together with a matching resistor and cables.

If you don't know how to chose this hardware below is a working combination listed:
Example led and power button combination
Example resistor (matched the mentioned led and button combination on the RPi GPIO)
Example cable

The following illustration shows the full connection:
GPIO 12 (pin 32) => cable => resistor => led+ connector => led itself => led- connector => cable => ground pin (any free ground pin)

The example cables can be connected without soldering. This connection is not bullet proof but does the job. The resistor can be soldered to the led+ connector and a cable can be plugged on the resistor and directly. (Soldering is possible but is not necessary)

Status led development (pull request): https://github.com/MiczFlor/RPi-Jukebox-RFID/pull/387