DIY Remote Control for Zoom H4n and Canon 60D
Within this project I developed a remote control for the Zoom H4n portable audio recorder and the Canon 60D DSLR camera. I want to fix a common problem lot of DSLR shooters have: Starting the camera and audio recorder simultaneously!
In my eyes there is problem with the H4n when using with a DSLR - You have to press the record button twice. Especially when filming events (e.g. wedding or birthday) the equipment has to be reliable. But with the H4n you can easily miss to tap the record button twice. As a result the sound partly or completely is missing.
The remote control prototype circuit connected to Zoom H4n audio recorder.
As said this project shall fix the problem. The goal is to develop an control circuit (like a remote control) that starts the H4n and the Camera (in my case a Canon 60D) with just on button. The requirements are:
- Small as possible to be able to put the remote control on the camera body.
- Indicator LED for record
- Clipping indicator
- Optional: AGC with Step-down und Step-up (Note: I decided to skip this point)
The prototype circuit in action.
H4n Remote Protocol
The protocol is RS232 with 3,3V level at 2400 baud 8n1. Marcus Wolschon has already decoded most parts of the protocol. For further details please see his blog.
| Button | Byte 1 | Byte 2 |
|---|---|---|
| Button released | 0x80 | 0x00 |
| Play | 0x82 | 0x00 |
| Record | 0x81 | 0x00 |
| Stop | 0x84 | 0x00 |
| Next | 0x88 | 0x00 |
| Prev | 0x90 | 0x00 |
| Volume + | 0x80 | 0x08 |
| Volume - | 0x80 | 0x10 |
| RecLevel + | 0x80 | 0x20 |
| RecLevel - | 0x80 | 0x40 |
| Mic | 0x80 | 0x01 |
| Line 1 | 0x80 | 0x02 |
| Line 2 | 0x80 | 0x04 |
| LED | Byte |
|---|---|
| Record | 0x01 |
| Mic red | 0x02 |
| Line 1 red | 0x04 |
| Line 2 red | 0x08 |
| Mic green | 0x10 |
| Line 1 green | 0x20 |
| Line 2 green | 0x40 |
Before H4n will reacts on commands from a remote control a registration sequence is needed.
| Sender | Byte | Description |
|---|---|---|
| RC4* | 0x00 | Send until H4n sends response. |
| H4n | 0x80 | |
| RC4 | 0xA1 | |
| H4n | 0x80 |
Pinout of H4n Remote Jack
Controlling the camera (Canon 60D)
The easiest way to control the camera is through a IR remote control. The protocol is simple and available at doc-diy.net. The good with IR is - it works for other canon cameras (i.e. ti rebel / D500) too.
Creating the Circuit
I used the ATMega168 Microcontroller from Atmel because it was available at the moment, you can also use a 'smaller' controller. A little program is used to sent commands to the H4n and to generate the IR signals for the Canon 60D. The circuit is powered by 3,3V through the remote jack on H4n directly, no additional power supply or battery required.
The start/stop trigger button is not build into the housing but connected through a jack and dedicated wire. With this the button can be placed anywhere for more flexibility. Two LEDs are used to indicate recording state and audio clipping. I used low current LEDs for this purpose as I do not know how much power the H4n remote jack can handle, so I am on the save side here.
The DIY remote control
Schematic (click to enlarge)
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