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Forum Index : Microcontroller and PC projects : Generating MIDI data with a MM...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9750 |
Hi all.  I have an idea for a MIDI sound machine using a VLSI codec chip(VS1053B). The spec is 8-bit WORDS, but 10-bit BYTES made up of a start-bit, followed by eight data bits, and finally a start/stop bit for framing. See the link above for even more technical information. The 1053 can also play OGG/WAV/WMA/MP3/MP2 and just about anything else you can throw at it(including FLACC with external DAC), but I am most interested in it for it's MIDI synthesiser. Complete modules can be had on eBay for about US$5 a board from listings like this one. The device talks to the host MCU using the SPI port, so my first thought was the standard MMBASIC SPI commands, but that does not support 10-bit SPI, only 8, 16 or 32. Next, I looked at the SPI Cfunction, and it DOES let you specify any number of bits per byte up to 64, so this is the one to use. The 1053 gives you access to the following instruments and also a good selection of drum sounds, so a MM-based drum-machine might be coming(using other MM input pins for sensor pads).....    Do any of the technical boys and girls here see any OBVIOUS problem with this concept as it sits now? Perhaps other members have even better MIDI synth chips they know about? Please post if you do. To be continued..... Smoke makes things work. When the smoke gets out, it stops! |
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Azure Guru  Joined: 09/11/2017 Location: AustraliaPosts: 446 |
MIDI is serial at 31.25Kbps. It is 8 bits of data plus a start and stop bit. This is a very standard serial transmission as a specific bps rate. The hardware interface uses opto isolation to stop those dreaded ground loops in audio systems. I worked with MIDI quite a bit back in its early days. I designed several high end controllers (back in the 8bit days) using multiple independent MIDI out ports when the Roland MPU-401 could only do 1 output per box. This was needed to try and reduce the latency of talking MIDI to several synths in a studio setup and keeping them within experienced muso's acceptable timing delays. There are plenty of great synth chips out there. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9750 |
Hi Azure. So, MIDI is 8N1 kind of thing? Do you have part numbers for the 'Great' synth chips? Smoke makes things work. When the smoke gets out, it stops! |
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| Azure Guru Joined: 09/11/2017 Location: AustraliaPosts: 446 |
The chips and synths I worked with were quite some time back. I think there is still some EMU chips available which is one chip that comes to mind, but they maybe a bit to complex. Probably much simpler integrated chips available out there today. If any others come to mind I will post. I was working in the higher end so the systems tended to be based on a MIDI chip but as part of a high end synth design. |
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| hitsware Guru Joined: 23/11/2012 Location: United StatesPosts: 535 |
https://moderndevice.com/product/fluxamasynth-shield/ or https://www.sparkfun.com/products/10587 work real well and add the ease of using an Arduino shield (if wanted) But you want to make your own board ? |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Yamaha YM3812. :) More info -> https://www.youtube.com/watch?v=QLJSdNYcdpk&t=542s Microblocks. Build with logic. |
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| hitsware Guru Joined: 23/11/2012 Location: United StatesPosts: 535 |
and this and this |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9750 |
Awesome! Thanks chums. I will check out all those links now.Smoke makes things work. When the smoke gets out, it stops! |
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| Azure Guru Joined: 09/11/2017 Location: AustraliaPosts: 446 |
I don't think the YM3812 is a MIDI synth. These were used on arcade video game boards back in the day (another industry I worked in before working in the computer industry): Frogger, Scramble, Moon Patrol come to mind. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9750 |
Yes, I have had a look at that chip, and it is not a MIDI synth, but a 9-channel sound generator chip. Would not work as a MIDI processor. Interesting chip for it's time though. Smoke makes things work. When the smoke gets out, it stops! |
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