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Re: 8-bit sound card on FPGA

Posted on 2018-09-25, 06:05

Do you plan to commercialize this? I'm sorry - all my projects are just for fun, no commerce... Usually I loose an interest before they are even "semi-mature", after that either they go on the shelf (most of the time), or I give them away to someone who can do their own research/design. My projects …

Re: 8-bit sound card on FPGA

Posted on 2018-09-25, 05:10

It is indeed pretty decent.. I have no PCs that need an 8 bit sound card but if I did I would be ok with using this for OPL2. Any chance of it doing SB conpatible digital audio in the future? Or is the project scope limited to only an Adlib card clone? Seems like I wasn't clear enough... Actually, …

Re: 8-bit sound card on FPGA

Posted on 2018-09-24, 17:01

I believe quite a bit of this noise is produced by OPL2 itself. Also don't forget FPGA is producing purely digital signal, and I use the world's simplest DAC (ONE resistor and ONE capacitor - that's all) to convert that digital one-bit signal to analog sound. FPGA's GPIOs are not made to provide …

Re: 8-bit sound card on FPGA

Posted on 2018-09-24, 16:21

matze79 wrote: why not implent opl2 too ? Are you talking about implementing OPL2 inside of FPGA ? Probably, final version of DAC part (sigma-delta instead of simple PWM, more bits etc) is here, the output - https://clyp.it/0f4ujcv5

Re: 8-bit sound card on FPGA

Posted on 2018-09-22, 20:50

Until I built a highly complicated :) test bench: https://content-12.foto.my.mail.ru/mail/nastalk/59/b-72.jpg I couldn't figure out how is that think working... Still not sure, if I can't read properly, or the datasheet is wrong about exponent calculation... Basically, I was shifting the mantissa in …

Re: 8-bit sound card on FPGA

Posted on 2018-09-22, 09:07

Does anyone know how does YM3014 work ??? The datasheet shows 16 bits for each SH cycle (3 unused, 10 mantissa and 3 exponent), but in reality YM3812 is sending 18 bits. I can’t recognize required data just looking at the logic anslyzer screen, and too lazy to experiment 😀

Re: 8-bit sound card on FPGA

Posted on 2018-09-21, 10:15

I dont see any DAC, I suppose you're doing PWM/PDM there for sound output ? Or maybe it is under the YM ? Yes, just a simple 8-bit PWM with one resistor/capacitor... Converting OPL2 output to parallel 16-bit format and sending only 8 MSBs to PWM (doesn't add a sound quality, but good enough for my …

8-bit sound card on FPGA

Posted on 2018-09-20, 19:16

While working (very) slowly on much more complex project inspired by the discussion, decided to make a simple SB-like card with DSP part (and OPL DAC) inside of FPGA, and original OPL2 chip just to test some ideas:

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