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Howdy to the Digilent-using people, Tony Barry writing. I am new to FPGA, but have a fairly strong background in EE and microcontrollers, C and assembler (mainly x86 but also Atmel AVR). My project is pro-bono for the amateur astronomy (occultation observing) community. Briefly, the occultation community observe the passage of asteroids in front of (generally dim) stars, and time the moment of eclipse and the moment of reappearance using strict UT timestamps to determine the position and possibly the shape of the asteroid from the knowledge of the time of the event, and the position of the observer on the earth. This information is passed on to the Minor Planet Center in Arizona for making improved ephemerides of asteroids, and sometimes to other science folk for various reasons. One recent occultation that gained some press was that of 2014 MU69 (the next target for the New Horizons probe after Pluto). You can read the story in the science press here:- https://www.space.com/37221-epic-success-observing-pluto-probe-next-target.html http://pluto.jhuapl.edu/Mission/KBO-Chasers.php Anyway, on to the point of this post. The limiting factor in occultation observing is the ability to see the target star (yes, that's obvious ... ) and there are two determinants of how dim a star you can see. Dimmer stars require bigger telescopes, and/or higher quantum efficiency cameras with lower noise. Amateurs do not have access to the budgets of professional scientists, so the telescope size is limited both by cost and by the ability to physically move a large heavy telescope. The camera cost is also limited. Within these constraints, it has been found that (arguably) the Watec 910BD board camera is pretty well the best (it was *not* used by the Johns Hopkins guys, but that's their story). However, the BD has some issues. The biggest issue is that it is a composite analog video camera (and that's ugly). Analog video really ought to be in the museums of this world ... but the cam can detect magnitude dimmer stars than comparable or more costly digital devices. However, the cam does have a digital video port, whose behaviour is documented, and this is the subject of this post. I would like to interface to this port. It is a BT.656 lookalike, which runs at a slightly higher clock speed (28.7MHz, vs 27MHz for standard BT.656) with 8 bits of data and two signal lines for vertical and horizontal blanking. 3V3 signalling and data. I need to pull in at least 16 frames (i.e. 756 bytes = 1 line x 525 lines = 400kB * 16 frames = 6.5MB storage) from this port, and do some arithmetic on those frames (basic averages, stats, etc), then shovel them into a UHS SD card or SSD local storage. It would be nice to have enough horsepower to do DAC and create some composite video out as a sanity check and local monitor. Now ... what kind of FPGA do I need to do this ? 1. Can run at more than 30MHz clocking in 8 bit parallel data. 2. Can store 10MB on board, and retrieve 1MB / sec from that store. 3. Can write 1MB / sec to an 8-bit DAC (the DAC can be an add-on, does not need to be on-board for this task). 4. Can write 1MB / sec to an UHS SD card (the socket can be off-board too). 5. Can run on 3V3. 6. Should not consume too much power. 10-12W would be around the maximum. 7. Cost is a consideration. Ideally, the FPGA would be less than $150 due to budget constraints. Well, that's my story. If anyone has some thoughts on the matter, please feel free to advise. Regards, Tony Tony Barry Sydney, Australia
Does anyone know of a small board available to interface to composite video ? High resolution is not required, but a small signal count would be good. I'm thinking of a small Pmod-like board that has a colorburst filter, 3 bit dac (so there are four input signals total) and maybe a couple of output transistors.