I am doing a project with my Canon SL1. Sound activated shutter. I have included sensitivity and delay pots so that the sense level can be adjusted, and a delay past the sense event so that I can catch the action at various points.
The sound board is pre-made based on LM358 (ebay). Not the greatest sound amp board but it works for my needs. I also attach a funnel to provide additional directional sensitivity w/o trying to make a shotgun nose piece. The bandwidth of the sound board is kinda crappy anyways. I am using the analog output and comparing that against a pot value for threshold.
With events that happen quickly it is best to have a mc and code that can run very fast. I am running Trinket @8Mhz and not using ISR as an event-detect method, but to save some clk time by doing only one analogRead() in loop (because they take some time) I only read the two pot values if a set button is high. I used a small tactile button with a pushrod and a led to indicate the push. Once set is pressed the two pot values are read and then waits 30sec so that the subject of the pic can be readied, then it runs in loop() until a sound is loud enough to signal the shutter cable. I am using a 2N4401 npn bjt as switch to camera cable.
For the last few lines, a short delay to allow things to settle, and resets threshold value high so that only one pic is taken. a press of the set button is required for the next shot (adjusting delay and threshold as needed before the press, etc).
All housed in a small Hammond 9v batt case, and modified so I can mount it onto my camera tripod w/ the camera. I did not want to hot-shoe it onto my Canon, it's just easier to swivel around using a swivel mount, etc.
There are many ways this can be modified for additional needs, like having a switch to change scales of delay. The dial scales I made in my CAD program, printed to paper, cut out, removable light glue to keep them in-place. For the threshold value, I have fixed resistors on each side of that pot so that on the very low side of sound input the threshold cannot be less than that, and on the high side of sound the threshold can be just a tad higher. This stops auto-fire on shutter (on the low side of sound), and allows threshold to be just above max sound to prevent shutter at all. But in other words, I tried to match the scale of sound levels into the pot movement, which meant using 3800 ohms on one side and 1500ohms on the other side of the pot.
It is still being built, but here's the code I am using.
Code: Select all
NO LONGER VALID, USING Trinket Pro Instead, KEEP READING THE POSTS