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GPCX161 I2C Tool Software and Parallel Port Interface

The I²C Interface

I've finished developing the I²C interface and software that will adjust the image settings on the Panasonic GP-CX161 cameras. The interface is very simple, and it should cost about $5 to build if you don't already have the components. The one drawback may be, the interface uses the parallel port, and most late model PC's are not shipping with parallel ports any more. After doing quite a bit of research, the parallel port was the only way to go and still meet my goal of keeping it low cost and easy. Using the USB or serial ports would drive the cost and complexity of the circuit too high.

You can purchase a PCI Parallel Port Card for less than $15. So if you don't have a parallel port on the PC you want to use, the cost of building the interface and adding a parallel card to your PC would still be the low cost solution. The software will run on Win98SE, so even a really old laptop or PC with a parallel port will get you in the game.

The first thing to do is build the Interface. (The schematic is included in the GPCX161 I2C Tool program.) The circuit consists of 4 resistors and 2 transistors. You'll also need a DB-25 male connector, a camera connector, and some wire. Resistor values close to the ones shown, and any general purpose NPN transistors should work.

You can fit the whole circuit on the back of a male DB-25 connector, and it will fit inside the plastic hood of a DB-25. You could also use perf board, etch a board, and/or put it in a project box. Any way you build it, the cable or wires running from the parallel port to the camera that contain the I2C clock and data lines should be less than 1 meter, or you could run into a phenomenon know as ringing. Ringing can be cured with a capacitor, but it's best to avoid it by keeping the lines short. I use USB cables cut from an old mouse to power my interfaces. If you don't have a USB port on the system you want to use, an old PC power supply can make a great 12 - 5 - 3.3 volt power supply.

However you get power, it should be a solid 5-volts of clean DC to supply both the camera and interface. Amperage draw is very low, so as long as you have at least 150mA it will get the job done. If you use an AC adaptor for power, test it's output with a meter to make sure it is in the near vicinity of 5 volts with no AC output. The standard wall adapters are notoriously high volts and noisy with a lot of AC output, so if you use one that "is" putting out 5-volts, you may want to add a little filtering to the output. Some of the better "brick" adapters, like the 5V PSP adapters are pretty good supplies.

The GPCX161 I²C Tool Application
	The "GPCX161 I2C Tool" software program has been tested on Windows 98SE, XP, Vista, and 7. There is a built-in manual of sorts, that includes the interface schematic and some information on operations with a little background on memory devices and CX161 operations. I've included the ability to save/write settings to/from disk, write to individual memory locations, load all default color or B&W settings, save comments for individual settings, and work with either the EEPROM or the DSP settings.
The software is free to use for anyone that has purchased a camera from me (RC). You'll find it here on the downloads page. The cameras have an EEPROM that stores camera settings while the camera is powered off. When the camera is powered on, the EEPROM settings are loaded into the DSP, and then the EEPROM is out of the picture until the camera powers up again. So when you are making adjustments or trying out new settings, you will want to work on the DSP, which is active controlling the camera, and you'll see the effect of any changes made to the DSP right away on the camera's video output. I have not had a lot of time to actually play with the program and test settings. My head has been under the hood and not driving so to speak. Below are the know camera settings that can be adjusted. There are 46 I know of, and the DSP & EEPROM can each hold 256 settings (a few locations are not used). So the law of probability would dictate that there are probably more settings that have not yet been discovered. The settings list is also included with the GPCX161 I2C Tool program that you can get on the downloads page.
Contrast Level - (Attained by adjusting Black(Dark) Level and Y(Luminance) Level Mirror Image (Horizontal Flip) Black(Dark) Level Chroma (Color) B-Y(U) Matrix Control (Ye Phase Adjustment: B Hue) Chroma (Color) R-Y(V) Matrix Control (R Phase Adjustment: R Hue) Chroma (Color) R-Y(U) Gain Chroma (Color) B-Y(V) Gain Further Y Gain (Luminance) Level Contrast Adjustment Nega-Posi (Negative - Positive Image) Further Black (Dark) Level / Contrast / Pedestal Adjustment Pedestal Adjustment Sharpness (Horizontal Direction Edge Enhancement) Sharpness (Vertical Direction Edge Enhancement) ELC Window H-Start ELC Window H-End ELC Window V-Start ELC Window V-End ELC Window V-End H-Start H-End V-Start V-End AGC (Automatic Gain Control) AGC (Max Gain) BLC (Back Light Compensation) ALC Target Level (Light Level) (Automatic Light Control/Brightness) Shutter Speed Control (ELC) ALC ON/OFF (Automatic Light Control/Brightness) Auto/Manual White Balance (ATW) Extended White Balance Extended White Balance Extended White Balance Extended White Balance Manual White Balance B Gain Manual White Balance R Gain Knee / Gamma S Gamma Correction Knee Point Y (Luminance) Level R-Burst Level Adjustment B-Burst Level Adjustment SYNC Level Adjustment ATW Lock (Auto Tracking White Balance Lock) Horizontal Phase Frequency Adjustment High Clip Adjustment