Those looking for a simple means to click the shutter of an SDM- or CHDK-controlled camera might want to take a look at these
. Although it talks about interfacing to a basic stamp, all you need at the camera end is a 5v supply and the receiver, I haven't measured the range yet, but it will certainly operate cameras atop my carp pole.
The receiver board has 7 pins:
1. 5v power
2. output voltage (connected to one of the output pins via radio)
3. common ground
4-7. 4 output channels
The 4 buttons on the transmitter connect (on a push) or disconnect (on the next push) pin 2 to one of the 4 output pins. While this does nothing that you can't do hacking a wireless doorbell, the amount of work needed to produce a working control is minimal - it took me just a few minutes of soldering to wire the receiver board to a USB connector (to plug into the camera) and a servo connector (to plug into a 4-cell AAA power supply). The board weighs just 5 grams - less than the two connectors!
Here's the circuit I built:
This looks like the same thing for those of us across the pond:
Would this system handle the current to control a small geared (pan) motor on one of the other output pins?
Since everything goes through the one chip on the board, I'd be dubious about putting much current through it. The CHDK/SDM method of triggering the shutter by applying 5v across the USB power pins draws virtually no current (the camera just senses the voltage - there's a very high resistance across the pins inside the camera).
If you want to drive servos or small motors I think you'd have to use a relay mechanism to switch them. I'm thinking of using one of these Pololu servo controllers - you can use some of the channels as analog inputs and write a script to detect when they go from 0v to 5v and thus control servos on other channels.
With respect to using a relay, do you think the receiver chip would be able to trigger one of these solid state relays ? Could I use the same 5 volt battery to power both the receiver (and input to the relay) and the output circuit of the relay/motor?
Good to see some more further movement in PAP! I have been using just this transmitter and reciever for some two months now, these are simple component just great for home made PAP electronics.
My primary goal was not to control the shutter - I let the GoPro do that for partial 'autoPAP' - but to control the tilt angle with a servo.
This resulted in this setup.
For my GoPro PAP-rig
I had a few problems with the signal. It was needed to attach an antenna to the reciever and to elongate the transmitter antenna to get to 10 meter distance. No idea why that was necessary.
I found out just very recently a cause. Although the AnyVolt micro is also a great nifty little device (tiny, completely freely adjustable and efficient because of switching technique), it heavily disturbs the signal when its close to the reciever.
With replacing it with a standard 7805 voltage regulator, no antenna elongation needed any more. So a lesson learned here. Tested it up to 50 meters, indeed far enough for PAP :) Could go further, with antennas the signal is enhanced.
That Polulo board is very interesting Dave! I will look into that. I used similar looking PPMencoder (that is a device to transform multiple remote control PWM signals to 1 PPM signal). It has an Atmel328P on it. It is simple to change it to a little Arduino device, if you're acquainted with that.
Effective length is very roughly about half wavelength, wave length of 433mhz is 70cm.
Sure there are more powerful antennas.
Other point is that reciever drops out if the servo is powered too. Atmel board keeps running. My provisional solution is: when it reads a signal from the reciever, I just control the servo for some short period. Then servo stops, reciever gets up again, and when the transmitter button is still pressed, the sequence is repeated. It already works good enough for me, but could this be solved in another way, while still using one battery?
Can you show us the whole wire diagram?
What pins on the USB do you use?
There's a webpage describing the PAP rig here (with circuit diagram and Maestro script) and very short YouTube video of it working here.
Anyway you can read more about it here.
PS I've rejigged the 433MHz PAP rig too - details here
I do have a question: Is there a way using SDM, or some external device, to actually turn the camera on, and then trigger the shutter. I am thinking about situations where I might want to set the camera, wait for the appropriate picture opportunity, turn the camera on and take the picture, then return the camera to an off-state.
I hope that I am not overlooking some very obvious solution within the SDM menu!