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AidanHockey5 / STM32_VGM_Player_YM2612_SN76489

A Sega Genesis music player based off of the STM32 BluePill board and real YM2612+SN76489 sound chips.
GNU Affero General Public License v3.0
107 stars 15 forks source link

update problem #9

Closed 6502bender closed 3 years ago

6502bender commented 3 years ago

Hello After upgrading mega blaster to v3.0, there were problems with SN76489. PSG began to sound terrible, extraneous sounds appear and the frequency seems to be floating Here is a link to a video for an example. https://youtu.be/bkRAT_hYAm4 There is no such problem in version 2.0. YM on the contrary, began to sound much better. thank.

AidanHockey5 commented 3 years ago

Unable to verify on the official Mega Blaster board. The PSG works just fine. I previously thought there might have been an issue, but I noticed that my PSG MUTE switch was set.

Sadly, since your board is hand-made, I won't be able to help you much. I would try and verify your hardware against the original schematic. Make sure the PSG's WE pin is connected to pin PB5.

6502bender commented 3 years ago

the fact is that if I upload the firmware v2.0, then PSG sounds as expected.

2021-02-25 20:07 GMT+03:00, Aidan Lawrence notifications@github.com:

Closed #9.

-- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: https://github.com/AidanHockey5/STM32_VGM_Player_YM2612_SN76489/issues/9#event-4377719021

jareklupinski commented 3 years ago

that's a wild board! Screen Shot 2021-02-25 at 3 21 10 PM rly the only diff in the sn-specific code is the amount of microseconds btwn writes, maybe on a hand-spun board this 3uS difference is the factor? I'm finding the PSG loves taking almost the entire sample to clock its data bus :(

6502bender commented 3 years ago

Thank you, so I will dig towards SN76489, but that will be later.

Now I started another experiment, it might be interesting.

https://youtu.be/YdA0xXXmrXM

The bottom line is to use the YMF276-M synthesizer

The YMF276-M was used in FM Towns II computers, and is kind of a lower power version of the YM3438.

The main feature of this chip (for me) is that it requires an external DAC (using the I2S interface). Therefore, the DAC with a preamplifier can be maximally isolated from the digital part, thereby seriously reducing digital noise, pickup, etc. in the sound.

The DAC used the BU9480F.

Next, I want to screw this chip to my console.