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Forum Index : Microcontroller and PC projects : Inexpensive MIDI Synth based on SAM2695
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| al18 Senior Member  Joined: 06/07/2019 Location: United StatesPosts: 222 |
M5Stack just introduced a MIDI synth module based on the SAM2695 chip for $14.50. The model is U187. https://shop.m5stack.com/products/midi-unit-with-din-connector-sam2695?ref=langship Both Digikey and Mouser will be carrying this module, though it’s not in stock yet. The module is interfaced thru UART thru a Grove connector. Wonder if this module could work with a PicoMite? |
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 7464 |
If it's only UART then it depends on an enthusiastic someone writing the MIDI protocol software. :) It will need to be someone with an in-depth knowledge of how MIDI works (or is willing to learn). It's not something to build into MMBasic as the normal COM ports should be fine. On the other hand, the VS1053 module will already play MIDI files and is supported by MMBasic as an audio device. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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PilotPirx Regular Member  Joined: 03/11/2020 Location: GermanyPosts: 92 |
I bought the U178 with the same SAM2695 Chip but without DIN connector and Jack. https://shop.m5stack.com/products/midi-synthesizer-unit-sam2695 I will try to use it with MMBasic (CMM2). Has anyone written a MMBasic MIDI player? So read in data from a midi file and output it as a MIDI stream on a serial port? |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10000 |
Does this do much more than the VS1053 which is fully supported by the PicoMite including MMBasic commands to send the MIDI to it. (NOTE ON/OFF etc.). Just needs someone to write the Basic code read in a MIDI file and then convert it to the MMBasic commands. |
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homa Guru Joined: 05/11/2021 Location: GermanyPosts: 451 |
A few months ago I started working with midi and a midi player in Basic. But only a beta to learn. I'm still struggling with the exact note length because of the tick calculation. I can look for the code this weekend and upload it here. I documented it quite well. As I said, only for learning and beta. Matthias |
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| PilotPirx Regular Member Joined: 03/11/2020 Location: GermanyPosts: 92 |
@homa Sounds good. Maybe we can improve it.Thanks. |
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| PhenixRising Guru Joined: 07/11/2023 Location: United KingdomPosts: 1134 |
So, although not a sound module, we should be able to hook-up a MIDI shield to the PicoMite, right?  |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7464 |
Here is the info on the Atari ST MIDI connections. There is a simple opto-coupler and a couple of transistors IIRC. I don't know if it's of any interest. Oh, just discovered that for the drivers they used 7404 inverter followed by 7405 0c inverter, not just transistors. They were posh. :) . Edited 2025-01-30 06:20 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4815 |
@Peter, There is a sound quality difference between the 1053 that is implemented in PicoMite, and the SAM2695 when it comes to MIDI. See this  I can imagine people looking for the SAM chip..... source Volhout Edited 2025-01-30 07:15 by Volhout PicomiteVGA PETSCII ROBOTS |
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| damos Regular Member Joined: 15/04/2016 Location: AustraliaPosts: 68 |
I bought one of these a few years ago and it is very good: Click here It has a lot of quite reasonable voices and supports all the things you expect like velocity, polyphony etc and is also reasonably low latency. The old DIN connections are really only good if you are already heavily invested in the DIN system. If you already have DIN MIDI devices, it is convenient for hooking up to micros and experimenting as the circuity is very simple. If you want to play from a keyboard, many of the modern controllers only support USB MIDI and don't even have the DIN ports so it can be hard to test your circuit. If you want to experiment with MIDI on micros and test using a low cost MIDI keyboard, you really need to have a USB MIDI Host controller. There is a company in the UK that has done all the hard work and supports all the Host protocol and outputs it as TTL serial. This saves a lot of pain and works well. |
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| al18 Senior Member Joined: 06/07/2019 Location: United StatesPosts: 222 |
The VS1053 and SAM2695 are similar devices, with the SAM2695 having more advanced MIDI capability, including a second bank of Roland MT32 compatible instruments. There’s an interesting discussion on Atariage forum, where Mytek discusses incorporating the M5stack U178 into his expansion board for Mytek’s NUC size Atari 8-bit computer at https://forums.atariage.com/topic/337657-invitation-to-the-launch-of-the-midicar-player/page/4/ Check out his video midway down the page. FYI Mytek was able to reverse engineer the $300 Hybrid Arts Midimate MIDI interface for the Atari 8-bits a few years ago, to an 8 pin PIC chip, an 8 pin Opto Isolator chip and a handful of resistors. More info here https://ataribits.weebly.com/midi.html |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10000 |
The point about the VS1053 is that you can just chuck a midi file at it and it will play it. It has the intelligence to understand the file header. The PicoMite firmware doesn't have to do anything on timing just feed its buffer. So PLAY MIDI takes a midi file, without having to interpret anything, and sends it as fast as the VS1053 can take it. Can the SAM2695 do this or is it expecting the midi commands to be sent at the appropriate timing? |
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| al18 Senior Member Joined: 06/07/2019 Location: United StatesPosts: 222 |
So the VS1053 is not compatible with the MIDI 1.0 specification, which states on page 1 the MIDI interface operates at 31.25 Kbaud, asynchronous, with a start bit, 8 data bits (D0-D7) and a stop bit. I didn’t realize how limiting the VS1053 was, not being able to be connected to a MIDI keyboard. |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7464 |
The VS1053 isn't a MIDI device at all, it's a multi-purpose CODEC that happens to be able to play MIDI data. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10000 |
It can be - its another mode of use |
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| PilotPirx Regular Member Joined: 03/11/2020 Location: GermanyPosts: 92 |
I have written a MIDI player that controls the SAM2695. The tracks are played one after the other, so a MIDI file in format 0 is ideal (format 1 - several tracks synchronized can be converted to format 0 with tools). I developed the IO board for the CMM2 G2 V2 myself. It has MIDI IN/OUT(Through), RS232, joystick, relay output, driver for WS2812 and a GROVE bus (I/O, I2C, UART) with 5 connections that can be switched between 5V and 3.3V. All pins to the outside are ESD protected. A demo-video: MIDI player When the project is finished, I will publish it. |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3299 |
Terrific project. Looking forward to seeing details. What's the little white device labelled "synth"? Can you share a link for it? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| PilotPirx Regular Member Joined: 03/11/2020 Location: GermanyPosts: 92 |
@lizby synth |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3299 |
Cool. Thanks. "Synth Unit is an audio module designed specifically for MIDI sound systems. This unit features the built-in SAM2695 audio synthesizer and accepts standard MIDI signals through serial communication. It provides various audio synthesis and processing capabilities, including audio synthesis, mixing, and sound effects processing." PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| homa Guru Joined: 05/11/2021 Location: GermanyPosts: 451 |
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