I have an old vintage camera that I gutted and put a raspberry pi into, similar to this project. I want to light an LED housed in the old flash housing when I hold down the button, as well as running raspistill.

The camera has a switch that closes when the old mechanical button is pressed, leading to a circuit I could connect an LED to. I can't modify the switch/LED part of this easily, but I could connect different wires from the Pi.

If I make the pin set to input with pull up or down resistor, it doesn't light up the LED (not enough current), but it triggers the raspistill script. If I change it to output once it senses button press, it shorts through the switch. What is the simplest way I can set this up without modifying the switch/LED part of the circuit?

Vintage Pi camera circuit

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    Why don't you just attach the LED to a different GPIO (an output) and trigger that from the raspistill script? You could then, e.g., leave it on for the duration of the call, so it carries meaningful information (as opposed to just how long you've held the button down, which presumably doesn't mean anything). – goldilocks Jul 2 '15 at 14:28
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    Does G here stand for ground? Then if Pin is set to input it shouldn't work as there is no electricity source. If G is 3v3 pin, then just add resistor to to the G, and switch to the other end of the resistor. – Piotr Kamoda Jul 2 '15 at 14:32
  • This circuit seriously misses a series resistor. If the pin is turned output (high) and the switch is pressed it's shorted to ground. Same goes for the LED - no current limiting resistor. – Ghanima Jul 2 '15 at 21:29

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