Looking for YM5214 MMC replacement

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By Alexey

Guardian (3235)

Alexey's picture

16-07-2021, 23:30

I suspect that in one of the CX5M that I am fixing now the MMC controller YM5214 is faulty. I've found the project that successfully replaced that chip with Altera 7128 FPGA:

https://www.youtube.com/watch?v=xgzbE-Q6iHU

The documentation in French can be still found here:
https://web.archive.org/web/20160528130351/http://msxotage.f...

Unfortunately the archive with the firmware is missing and I can't find it anywhere. Does anyone have this archive? The old path is this one:
http://msxotage.free.fr/fichiers_tmp/signaux_ym5214_v7_18_04...

My idea is to recompile this firmware for Altera 7160 FPGA and use the board similar to our YM2148 emulator:
http://rbsc.su/en/completed_projects/#0017_YM2148_Emulator

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By sdsnatcher73

Prophet (2316)

sdsnatcher73's picture

17-07-2021, 00:00

Check this site: http://mymsx2.free.fr/menu2_msx.html hardware 03/2014 Remplacement d'un YM5214 ( MSXEngine du MSX1 YAMAHA CX5M ) par un EPM7128. And a video here: http://mymsx2.free.fr/montages/ym5214toepm7128/ym5214toepm71...

Possibly MetalGear2 still has the code.

By Alexey

Guardian (3235)

Alexey's picture

24-07-2021, 16:06

Looks like the author decided not to reply to me. This is very sad...

By Pentarou

Champion (400)

Pentarou's picture

24-07-2021, 16:52

I have the ym5214_to_epm7128_v7_18_04_2014.pdf, in it there's the equivalent schematic + lots of info.

Do you want it?

By MetalGear22

Supporter (5)

MetalGear22's picture

24-07-2021, 17:04

Hello,

@Alexey: Check your mailbox

By Alexey

Guardian (3235)

Alexey's picture

24-07-2021, 17:27

Hi Philippe, glad to get in touch! I found the PDF already, but I am missing the archive with the firmware. Would appreciate if you could post it on your website or send it by mail.

By xicor

Supporter (2)

xicor's picture

15-10-2021, 13:23

Hello all,

Sorry for hijacking this thread, but it does intersects with the death of my YIS503. Obviously the ym5214 failed. On the search for a replacement, I found the MMC to be pure unobtainium.

Searching the web found the pdf above, detailing the work done by MetalGear22, and soldiered to reproduce it the best I can. I had to make assumptions, that may be the source of my bump on the full repair of my YIS503.

I made and adapter, using cpld EPM7128slc84-15n, and the pin distribution as the schematics.


(The pcb is not a definite version because of tolerances with the metal "shield/casing")

Now to the point that I'm having difficulties, the YIS503 boots to basic, but no "key press" is scanned. I have isolated to the cpld, because I do have a functioning CX5M that temporarily donated his YM5214, and everything worked as expected.

The keyboard scan is operated by the PPI on io port AAh and A9h. So I would guess that the decoding of PPI enable may be at fault, but if so it would afect also the decoding to VDP and SSG ?

Also, in the CPLD implementation schematics, a 74368 is used to invert A7, why not a 7404?

The same is done to invert RFSH signal @ SLTSL section. Is it to comply to timing requirements ?

The I/O decoding portion is also a bit different from the technical reference, where /IORQ, /RB, A7, A6, A5, A4, and A3 are used to decode the i/o ports of PPI, VDP, SSG and PRT, but on CPLD M1 is used. The funny this is that the signal /RB is nowhere to be found on schematics or pinout of YM5214. (Yamaha Computer MSX Series Technical Summary). Guessing a probable typo from Yamaha.

Where can I start debugging ? Any ideas ?

By Alexey

Guardian (3235)

Alexey's picture

15-10-2021, 16:49

There already exists the working solution from MetalGear22. He even made a new, better board with a different FPGA to replace the broken YM5214 chip. He promised to send me the bare board so that I could assemble it myself, but I haven't heard from him since August 31. I hope he is ok...

By MetalGear22

Supporter (5)

MetalGear22's picture

15-10-2021, 20:31

Hello Alexey,
Strange, I sent a card to your address.
I check.

By Alexey

Guardian (3235)

Alexey's picture

15-10-2021, 21:16

Hi Philippe. Sadly, no package has arrived. I also sent you 3 mails in the last few weeks asking for the POF file and the schematics so that I could assemble the board myself and program the chip. Maybe they ended up in your SPAM folder?

By xicor

Supporter (2)

xicor's picture

19-10-2021, 18:09

Making progress:

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