| Products > Test Equipment |
| Building my own scope |
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| rob77:
--- Quote from: balnazzar on October 20, 2022, 09:44:19 pm ---Now that could actually be a very effective starting point... --- End quote --- yes, good starting point to get onboard with FPGA and writing software for linux. if you will go for that capture board then obviously you have to desolder the FPGA to figure out what is connected to which io and create a io pin map (ring the traces through with continuity tester) and then reball the fpga and solder it back. i'm planing to do that once i'll have some time, but it's like that for few months already :D i'm planing to rip out the hdmi sink and the video-processor , make a small daughter board with bus drivers(level shifting) and use it for high speed data capturing (even using the HDMI connectors). as you see on the picture i have the pin header populated on one of the boards, and can confirm it works with USB blaster and Quartus no problem, i can read and write the configuration memory through the FPGA. |
| rob77:
--- Quote from: tggzzz on October 20, 2022, 09:51:18 pm --- --- Quote from: rob77 on October 20, 2022, 08:33:32 pm --- --- Quote from: alm on October 20, 2022, 08:23:55 pm ---If you want high bandwidth, then an FPGA might be a good way to accomplish that ;). --- End quote --- FPGA is the only way ;) there is no RT OS capable of sampling with low jitter at any reasonable sample rates... If you do the sampling on the FPGA (low jitter), serialize the data, send it to the computer, then processing on the computer is absolutely not critical.. the only concern would be to have enough processing power to get reasonable waveform update rates on the screen. --- End quote --- There is a halfway house. Sample using a low jitter clock. Put samples in a FIFO/queue. At the computers convenience, take samples from FIFO at computer's convenience. Provided the computer can take the samples at a mean rate that is higher than the sampling rate, all is well. The averaging interval for calculating the mean rate is closely tied to the depth of the FIFO. --- End quote --- isn't that exactly what the FPGA + USB fifo + OS device driver combo does ? ;) |
| tggzzz:
--- Quote from: rob77 on October 20, 2022, 10:17:18 pm --- --- Quote from: tggzzz on October 20, 2022, 09:51:18 pm --- --- Quote from: rob77 on October 20, 2022, 08:33:32 pm --- --- Quote from: alm on October 20, 2022, 08:23:55 pm ---If you want high bandwidth, then an FPGA might be a good way to accomplish that ;). --- End quote --- FPGA is the only way ;) there is no RT OS capable of sampling with low jitter at any reasonable sample rates... If you do the sampling on the FPGA (low jitter), serialize the data, send it to the computer, then processing on the computer is absolutely not critical.. the only concern would be to have enough processing power to get reasonable waveform update rates on the screen. --- End quote --- There is a halfway house. Sample using a low jitter clock. Put samples in a FIFO/queue. At the computers convenience, take samples from FIFO at computer's convenience. Provided the computer can take the samples at a mean rate that is higher than the sampling rate, all is well. The averaging interval for calculating the mean rate is closely tied to the depth of the FIFO. --- End quote --- isn't that exactly what the FPGA + USB fifo + OS device driver combo does ? ;) --- End quote --- Probably, but omit the FPGA and have a FIFO that isn't tied to a communication device ;) Cats? I know lots of ways to skin them ;D |
| BillyO:
I built a scope once. Back in 1978. It was a Heathkit. The only way I'd build a 2nd one is if I found an un-built Heathkit kit. Of course that would probably cost me as much as a decent new car, but a whole lot less than a Keysight 8ch 32GHz jobbie. I wish you success. This is a bigger project than I would ever take on as a hobby. |
| rob77:
--- Quote from: tggzzz on October 20, 2022, 11:19:49 pm ---Probably, but omit the FPGA and have a FIFO that isn't tied to a communication device ;) Cats? I know lots of ways to skin them ;D --- End quote --- and how exactly would you connect it to the computer ? |
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