EPSG for NES and Famicom (expansion sound module)

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Perkka
Posts: 20
Joined: Fri Jul 05, 2019 2:29 am

EPSG for NES and Famicom (expansion sound module)

Post by Perkka » Tue Apr 27, 2021 1:02 am

I just wanted to share this here, most people on the NesDev discord are already aware.
I've been working on a little project for the NES to actually get a use of the expansion port.
It's a sound expansion using the Yamaha YMF288 chip.(I'ts more or less the YM2608 also called OPNA but without ADPCM)

It is more or less finalised now and works.
It can use $4016 to send nibbles of data or the EXP pins on the cartridge to route down addressing from the cart for easier addressing.

There is stereo output from the 3.5mm output on the PCB, but it does forward audio to the onboard RCA jack on the NES too. and enables Famicom expansion audio.

It fits nicely into the Expansion cutout on the NES:
IMG_0434.JPG
If you'd like to hide it under the cover for the expansion port it should be possible to drill a hole through the fastening clip.
IMG_0435.JPG
I did also make a Famicom version
IMG_0463.JPG
It would fit like this and use an addon PCB for configuring the EXP addressing:
IMG_0462.JPG
https://www.youtube.com/watch?v=sUJsiCD8CGg
https://www.youtube.com/watch?v=8EaxvQikh3Y

mkwong98
Posts: 263
Joined: Mon May 30, 2011 9:01 pm

Re: EPSG for NES and Famicom (expansion sound module)

Post by mkwong98 » Tue May 04, 2021 8:55 am

Hi Perkka,

Are you the same person as the one who added EPSG to Mesen? I'm trying to update the documentation and in the Advanced tab of Audio Options form there is a EPSG setting which needs to be documented. Can you write a short description of what it does? Thanks

Perkka
Posts: 20
Joined: Fri Jul 05, 2019 2:29 am

Re: EPSG for NES and Famicom (expansion sound module)

Post by Perkka » Tue May 04, 2021 1:54 pm

mkwong98 wrote:
Tue May 04, 2021 8:55 am
Hi Perkka,

Are you the same person as the one who added EPSG to Mesen? I'm trying to update the documentation and in the Advanced tab of Audio Options form there is a EPSG setting which needs to be documented. Can you write a short description of what it does? Thanks
Yes that would be me (with a lot of help), the "EPSG Clock Frequency" is the base frequency the Yamaha Sound Chip works at, it mainly affect pitch and timings. simply how it calculates sound.
The YMF288 it made to work at 8Mhz, but I run it at 3.579545 so it matches up with S5b.

mkwong98
Posts: 263
Joined: Mon May 30, 2011 9:01 pm

Re: EPSG for NES and Famicom (expansion sound module)

Post by mkwong98 » Wed May 05, 2021 9:01 am

Perkka wrote:
Tue May 04, 2021 1:54 pm
Yes that would be me (with a lot of help), the "EPSG Clock Frequency" is the base frequency the Yamaha Sound Chip works at, it mainly affect pitch and timings. simply how it calculates sound.
The YMF288 it made to work at 8Mhz, but I run it at 3.579545 so it matches up with S5b.
Thanks! I'll add this to the documentation.

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