Bruxton Corporation SIDX sample program description, RaspberryPiGenerateTrigger.

RaspberryPiGenerateTrigger

You can use a Raspberry Pi to generate camera trigger signals for testing. The sample python program RaspberryPiGenerateTrigger.py generates an external trigger signal using a Raspberry Pi GPIO pin. The trigger timing is not precise, because the Raspberry Pi software timing is not precise. However, the Raspberry Pi is an inexpensive and convenient platform to use for experimenting with trigger signals.

The AcquireContinuous and AcquireEpisode scripts operates the camera in free-run trigger mode, that is, the camera runs as fast as possible. If you want to experiment with triggering the camera using an external signal, modify one of the scripts to set external trigger mode.

RaspberryPiGenerateTrigger.py is written assuming that you have an external inverting buffer for the trigger signal, so RaspberryPiGenerateTrigger treats GPIO output high as camera trigger input low. The Raspberry Pi uses 3.3V I/O and most cameras use 5V TTL-compatible signal levels. These signal levels are, in principle, compatible, but it is safest to use a buffer between them. For prototyping, you can easily assemble a buffer circuit on a solderless breadboard. Some hints:

Some construction notes for the circuit: