On 2015-06-01 20:24, Mark J. Blair wrote:
> I'm also working on getting design details from Silicon Labs for one of their > inexpensive single-chip TV tuners under NDA. If the Crazy Cat Lady project > moves forward, that chip might come in handy. If I use that chip, I'll need > to consider whether the NDA terms would preclude me from sharing my own IP > that uses the chip, since I'd prefer to share my schematic and firmware. But > if the NDA would disallow that, then I'd either need to close part or all of > my design, or pick out a different tuner option. As far as the crazy cat lady project, as I was trying to explain earlier.. my $.02 which maybe redundant to your own thoughts: VIDEO ADC/DECODER You can certainly use an off-the-shelf part as there are 47 from 5 companies on Digikey alone in solder friendly packages. However if the classic machines you are targetting are producing a clean conforming NTSC_M/J, PAL_B/G/N, or SECAM signals, stock video decoders on most converter boxes would work perfectly already. I doubt you will have much luck with the NDA process explaining a hobby cause but worth a try. Even if you are successful, make sure the parts you are looking at are readily available in 10s and 20s quantity through a distributor chain at a reasonable cost. That may be a second hurdle if it's fairly exotic. What SiLabs part are you looking at? I can't find any recent video decoder offerings. GENERIC ADC/DSP ANALYSIS This is the harder path to go down. You will need a symbol rate of at least 54 Mhz from a single or two interleaved ADCs to have a shot at at least 50% phase accuracy (NTSC = 13.5 MHz). There are some relatively inexpensive options, but I suggest getting a lot of input from folks and other reference designs on the best way to build an analog front-end for composite. And only do composite/S-Video. There are already commodity solutions for stepping down broadcast RF frequencies to base-band. After that, you will need something fairly hefty at the start to find the characteristics of the signal and align the sampling. Then you just need to track clock drift and adjust a VCXO. Straight-forward in hardware, but I doubt many people will have the experience to add new software support for <insert eclectic hardware platform with slightly non-standard composite output here> and fix bugs when they occur. So set expectations on your time early with respect to project support. SOC/ZYNQ/MARKET The fact you mention ZynQ throws up a few warning flags for me. It's probably overkill, it's expensive in low quantities through normal distributors, and it's not very hobby friendly. $65 for a '010 alone + DDR3 + BGA assembly would drive the resulting cost for you to make these boards well beyond $200. And your market is small - vintage computing folks w/o a CRT on a limited budget. Considering that, you probably should not try to build the processing core yourself. Run the ADC output or the video decoder Bt.656 output into a stock board like a Parallella, BeagleBone Black, or other EVM that has the processing power, HDMI output, and input interfaces you need; especially to start with. Then go full custom later. -Alan
