RISKY MSX Rev2

[arkadiusz.makarenko]

Thanks to @NYYRIKKI who helped me pull off the MSX side of software use of this cart became even easier. No need to push a button on boot, everything can be done out of MSX keyboard.
On top of it opamp on SCC does the job.

Some promo video

[arkadiusz.makarenko]

I have started looking at accuracy of SCC.... and it is really bad.
Low frequencies seems to be fine, but higher one seems to be muted a lot.
I need to think of how I can troubleshoot it. I have few ideas but it has to start from collection debug data.

[arkadiusz.makarenko]

I am redesigning how DAC data is being transferred,and how next sample is generated. It is to make sure all data is ready on time, and dac value change is done in right point of time.
I have ordered one more opamp type which is much better suited for audio and I will compare if change anything.

[arkadiusz.makarenko]

I have solved main issues with SCC. I had badly misconfigured timer. I have mixed up settings on prescaler and period, so in practice I have divided timer clock by 2.

Now it sounds much better. There is still sound dullness, this is either limitation of DAC itself or my opamp circuit. Since I solved the main problem I can focus on sound quality.

https://youtube.com/shorts/G8YZQUP4joE? ... yfUirD68Rj

[arkadiusz.makarenko]

I have released new firmware. Rev 2.1.4. At last I have all SCC and sound generation timings right!

@PhilC If you still use my cart, then I would strongly recommend upgrading to this firmware.

[PhilC]

I have released new firmware. Rev 2.1.4. At last I have all SCC and sound generation timings right!

@PhilC If you still use my cart, then I would strongly recommend upgrading to this firmware.

Yes, still use it as it's so much easier than the others to use.

Looking forward to hearing the SCC changes

[arkadiusz.makarenko]

I have released v2.1.5. This enables buffer on DAC. This makes sound a little bit better.
I have new branch for V307 chips. Separate clock settings are needed.

@Higgy
@terriblefire
I recommend moving to this firmware as you will be able to hear SCC sound much better on Rev1 boards.

I have added v307 branch to support other compatible chip types.
Those need to have a little bit different clock configuration. Generally it works ok, but 5% slow SCC sounds bad.
It is time to automate the build...

[Higgy]

Thanks for the heads up, I will update.

I've been working my way through those Tape-to-Rom conversions and been getting very good success rate in running them. I had a bit of a break from it to look at something else, which is now done.

[arkadiusz.makarenko]

I have released v2.1.6. It is irrelevant change for now. It provides support for more expensive CH32V307 chip. Just in case.

My next steps will be focused on in-application firmware upgrade.
It is difficult to get to internal bootloader space, and I don't have enough space to fully embed it into firmware.
I have few other ideas to work round those issues.

[PhilC]

@arkadiusz.makarenko sorry its taken mea while but just loaded up the V2.1.6 firmware and put Space Manbow on and it sounds much better now and the Graph button pressing works great.