Controlling a DVR623V with a Propeller

rjo_

I recently ordered a pair of DVR623V from Electronics123.com. My intention is to build a stereo camera, that I can control using my PropPhone(the duck tape version is shown[noparse]:)[/noparse]. The guys at Electronics123 are nice, very helpful, and fully competent.

The unit is easy to use and works as advertised. There is an external trigger mode, for both the DSC and DVR modes, which simply requires grounding the trigger pin. Switching between DSC and DVR modes is equally easy by grounding another pin at start up.

I would like to be able to remotely configure the cameras. Normally a key pad is used and I want to replace the key pad with a Prop. A diagram is included in the pictures.

There were a few days between order and delivery, so I tried to estimate the voltage at the key pad pin of the camera. Ohm's law failed me[noparse]:)[/noparse] The voltage is about 2.7V. Since I incorrectly estimated the pin voltage, I now suspect that I don't know what I am doing[noparse]:)[/noparse]

What I think is happening(please correct me if I am wrong) is that a voltage drop is being sensed by the camera at the key pin and the size of the drop determines how the camera interprets the key event.

The diagram is the only documentation available.

I would like to control the camera using a single pin. Am I correct in assuming that a couple of digital potentiometers and a fixed resistor will do the job?

Thanks

Rich

rjo_

I was a little tired when I posted my note last night. So, just to elaborate a little. My first idea... which didn't work out too well... was to simply place an NPN transistor between the camera "key" pin and ground and then to use a high frequency PWM from the Prop to effectively limit the flow out of the key pin to ground. The camera didn't like this. It did respond to it, but appeared to think that I was pressing a couple of different buttons in rapid sequence. What worried me is that my synthetic key press only lasted 1/4 second, but the camera acted as though it was getting a key press long after my signal stopped. I didn't have a lot of time to look at it. One pin, very elegant, but

should I stick with this approach?

Other than using a pair of digital pots, the last idea that I had (which I like but not as much) is to essentially rebuild the keypad, using one transistor and one resistor to replace each button/resistor pair and control the key selection using a shift register to toggle the transistors... two prop pins... I could live with that.

Whatever I do, I will be posting complete info on the forum.

In addition to being able to remotely configure the cameras, since the cameras have SD cards and output video, this type of control would allow a presentation to be preloaded on the SD cards as a series of jpg or avi files and then be sequentially presented using the Prop to control both video outputs for a 3D presentation.

Thoughts?