(updated 3/16/01)
I had this idea to use a web cam as a video recorder in a rocket.
What I was hoping to accomplish with this was a cheap, digital video recorder.
I had an extra b/w quickcam that I was going to experiment with. This is one of the parallel versions. I think a parallel version would be easier to capture because all you would have to do is when a data byte is available on the parallel port of the camera you just tell the memory to read it off the bus. This way all you need is some memory and a clock/counter to increment the memory address.
In theory this sounds easy but when I started looking into memory options it became apparent that the cost of several megs of memory was going to be quite high. That was when I started looking into DRAM. DRAM has the drawback of needing to be refreshed all the time. This refresh increases the complexity of the circuit. But one advantage of using DRAM is that surplus memory from computers can be used. 32pin simm clips for computers in 4 or 8 meg are cheep because no one wants them anymore.
Since my experience with microcontrollers is limited to the PIC16f84 I had to use 3 of them to design the camera. One is used to controll the refresh of the memory. The second one is used to controll the web cam and the third is for general databus control.
Here is a partial schematic of what I was going to build.
I never completed it because the availability of parallel web cams has declined in favor for the USB version.
I may continue the design using a USB version of the camera. Microchip has come out with a version of their PIC that has an integrated USB port. Also I came across a brand of Compact Flash memory card that has a built in USB port. Of course I have a concern as to how long this company will make this CF card and also they have not responded to my inquiry for data on the USB port. Certainly this would be the best route because I could take the card and plug it directly into my Pocket PC and view the images/movies.
Maybe more on this later.
I have come to the conclusion that I have to design this around the USB web cam and that it must be capable of at least 4 seperate cameras. Of course it will work with only 1 too.
Secondly it has to use compact flash memory cards for storage. I have some info about connecting a PIC to a CF memory card.
This would allow the system to be user definable.
For the budget concious they could use 1 camera and a 32meg CF card.
If it was a big L3 bird then they could mount cameras in the interstage coupler, one looking rear, one looking forward, and one looking out the side. And for storage they could slap in a 128meg CF card. Or maybe a 1gig microdrive.
Using the CF card seems easy enough but I am waiding through the FAT disk drive specification so I can store as a file that can then be read by any laptop with a PC card slot.
Interfacing to the USB port may be a different story. I'm really just starting to look through the spec and it may take some doing to get this to work. I didn't know how smart the USB connection was. Its nothing like RS-232. I would build 1 USB port into the circuit and if you wanted additional cameras you would attach a USB hub and theoretically you could use up to 255 cameras.
You will hear more from me when I get these things put together.