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Welcome to Freezer project

Aim of this project is creating a device to trigger multiple DSRL cameras and a set of studio strobes based on the Arduino hardware.

Both cameras and flashes can be connected to the device by cables or using one or more Pocket Wizard. The device itself may or may not be triggered by a Pocket Wizard.

Canon 550D schema

In the real case scenario, Freezer will be used to control several cameras Canon 550D. Each camera focus and shutter can be controlled by a sub-mini phone stereo 2.5mm male plug like the one described by the following picture.

When the focus line is short circuited to the ground, the camera automatically focuses on the target. If the lens is set to manual focus or if the camera "Shutter/AE lock" custom function is set to disable the autofocus, the camera simply goes into an active state.

When the shutter line is short circuited to the ground the camera shoots. The shutter response is faster when the camera is in active state.

The equivalent circuit of a Canon 550D is shown here.

The camera focus/shutter button shares the same circuit of the stereo plug.

The above schemas have been taken from and the values retested for the Canon 550D. The measured values are equivalent to the ones in the table.

Voltage (no load) 3.3 V
Threshold voltage 1.8 V
Short circuit current 68 µA
Current at threshold voltage 30 µA

Arduino Nano

To trigger all the cameras at the same time the following board has been choosen: Arduino Nano V3.0 AVR ATmega328 P-20AU USB board 3.0. All the information about Arduino boards can be found at the following link.

The Arduino Nano has been chosen because it is a small and vesatile circuit, highly configurable. It is practically a mini computer programmable in C++ language that can be controlled and powered by a PC using a USB cable or live independently while powered by a 9V battery. Following a reference schema for the board.


In the construction of Freezer the following components have been used.

Circuit schema with test LEDs

Following a schema with all circuit connections.

Motherboard PCB construction

The PCB has been developed with an open source software called Fritzing that can be downloaded for free from

Here you can download the Fritzing project file.

Here you can download the Gerber files, the industry standard format use in PCB production, which have been generated by Fritzing. This files can be sent to a PCB factory to produce the printed circuit.


As explained above the Arduino motherboard can be programmed in C++. The source code is currently strored by Google Code via a Subversion repository and it is available for free under LGPL licence.


This is the latest working code being released

External links



Camera Axe

All-in-one Remote


Hi there, Many thanks for your brilliant projects. I am setting up a little studio at home with some cameras and had a few extra questions on the Freezer setup. Is the board triggered by some form of intervalometer or switch plugged in to "IN1" or can you trigger the system to fire through a command on your computer. Ideally I'd like to trigger the system through a key press on my computer through the Arduino software. Is the sketch setup to do this? Apologies for my ignorance but this is my first Arduino project and I'm not great at understanding the code. Many thanks, Jack

The IN1 is essentially a switch. When the switch is short-circuited it triggers the arduino program that properly triggers the cameras.
How you short-circuit this switch is up to you. You can insert into the IN1 jack a Pocket Wizard to remotely trigger the circuit or you can insert the same cable that you would use to manually trigger the camera. You can even insert a screw driver into the IN1 and it would work.
I do not know at the moment know how you can trigger it from a computer. Maybe you can use a usb cable and another arduino that is then plugged into this crcuit. What you essentially need is USB controlled switch.