My ambition to film underwater
I decided to create this Sony interface and program as part of a strong desire to get into underwater video. I've been taking stills for a few years now. After some research I decided the Sony HC7 camcorder, with its ability to film HD, was just the job. I purchased one and went hunting for a underwater housing. There are many housing on the market, and a wide range of cost. Some have mechanical controls while other are electronic. I have never trusted an O-ring so went for electronic controls. The company I have been talking to is Birchley Products (http://www.birchleyproducts.co.uk/) who make a very nice housing and lighting system. They currently have a limited Sony LANc control but are enthused to expand the controls with my help. So a project for me was born and much research later this is the result!
Sony LANc Control
The Sony LANc control is similar to RS232, except it's inverted and has a long stop bit. A very good description of the protocol and known codes can be found at http://www.boehmel.de/lanc.htm.
The protocol has 8 bytes. Bytes 0 & 1 are to control the camera while bytes 4-7 give the camera status. Control bytes have to be transmitted synchronously to arrive when Bytes 0+1 are expected. That's tricky from a programming point of view.
Fortunately you can buy a chip that does all the RS232 to Sony LANc conversion for you. This makes the programming part real easy. The chip is the ELM 624 (ELM624DS.pdf) and can be purchased from Canada for about £12 from here http://www.elmelectronics.com/index.html.
I'm indebted to Eric Cairon (http://www.ritonworld.com/) whose web site provided the core of the information I have used to develop my program.
The ELM624 interface board
You have two choices, build your own or buy one from Underwater Minnesota
To build your own you will require the following:
- Lanc circuit PCB layout
- The ability to etch a PCB. You can find some guide notes here
- The components listed here:
| ELM 624 | 1 |
| LM7805 regulator | 1 |
| 2N3906 transistor | 1 |
| 100 NF capacitors | 3 |
| 27pf capacitors | 2 |
| 100 ohm | 1 |
| 4,7 Kohm | 1 |
| 10 Kohm | 1 |
| 33 Kohm | 1 |
| 100 Kohm | 1 |
| 1N4148 diode | 1 |
| 3.579545 Mhz Crystal | 1 |
| 9 pin female COM port connector | 1 |
| 2.5mm stereo jack plug | 1 |
| Cable |
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The program
I have used Visual Basic Express 2008 to develop the program. You can download it free of charge and modify my source code linked below:
The links:
- Get Visual Basic 2008 Express from here (http://www.microsoft.com/express/vb/)
- My LANc Control Source Code ZIP
- My Sony LANc program install
- My Sony LANc .EXE program
I wrote the program to interrogate the Sony HC7 camera codes. The program has two forms. The first is to set up the program. The program looks at your PC to find the names of the active COM Ports. It also sets by default known Sony LANc codes for certain functions. There are six assignable text boxes where you can experiment with alternative codes. The form looks like this:
The second form is the control panel. The control features it has are as follows:
- Power Off
- Mode Switching: Camera / SD card / VTR
- Time code reading
- Camera status and raw status code received
- Battery Low warning
- Camera mode: Record, Record pause, Zoom, Auto / manual focus, write
to the SD card, Photo capture, Backlight exposure, Assignable buttons
1-6.
- VTR Mode: Play, Stop, Pause, Search rewind, Search forward, Fast rewind, Fast forward.
