MIDI support?

alraz

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Sep 14, 2019
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Was wondering if there are any plans to support MIDI output (or input!) either directly or through add ons.
 
May 22, 2019
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At the moment, there don’t appear to be plans by David or the team to build an official MIDI interface.

However, MIDI certainly is feasible through the expansion ports. It would require a custom PCB, however, and it would obviously also require new software for the system.
 

christo

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Sep 16, 2019
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If I understand correctly, MIDI is elecrically equivalent to RS232 - I'm a big fan of supporting that (and MIDI also). If there is a header or some other RS232 port, then a MIDI interface cable is all you'd need.
 
May 22, 2019
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If I understand correctly, MIDI is elecrically equivalent to RS232 - I'm a big fan of supporting that (and MIDI also). If there is a header or some other RS232 port, then a MIDI interface cable is all you'd need.
No, MIDI is a balanced signal, where RS-232 is unablanced. MIDI also runs at (IIRC) 32kbaud, which is not a common speed for RS-232 interfaces.

The best choice really is to use a MIDI transceiver, although it can be faked with the right balancing circuit.

 

Ohjurot

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Sep 13, 2019
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I‘m currently working on a midi expansion card. I just startet building basic midi circuits and tinkering with the midi protocol. I will soon start a new thread here to get some detailed information about the expansion ports. I don’t know how far this goes but if there is enough demand i may sell the card. But for now I have to work on an other project. I will keep you updated!
 

easyprototype

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Sep 21, 2019
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Honestly I think the Commander X16 should feature more IO ports as standard. Namely the MIDI ports we are discussing here and at least a serial port. a MIDI port with super low latency is one of the features that made the Atari ST survive to this day. MIDI ports with the 2 onboard sound chips would make the X16 a must for chiptune/synth lovers and composers. BASIC commands for the MIDI port could be added too, opening more options :)

A I2C port adressable directly from the address/data bus (ex: PCF8584) would be amazing for interfacing all those nifty breakout boards available to electronics hobbyists, but such chips a quite specialized. Okay, the I2C should be an expansion card...
 
May 22, 2019
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Honestly I think the Commander X16 should feature more IO ports as standard. Namely the MIDI ports we are discussing here and at least a serial port. a MIDI port with super low latency is one of the features that made the Atari ST survive to this day. MIDI ports with the 2 onboard sound chips would make the X16 a must for chiptune/synth lovers and composers. BASIC commands for the MIDI port could be added too, opening more options :)

A I2C port adressable directly from the address/data bus (ex: PCF8584) would be amazing for interfacing all those nifty breakout boards available to electronics hobbyists, but such chips a quite specialized. Okay, the I2C should be an expansion card...
GPIO is definitely a worthwhile thing on modern microcontroller based systems, and having SPI, I2C, and RS-232 I/O would be super useful. On the other hand, all of these things require additional hardware to support, and the team has decided to focus first on making the core computer work as well as possible, leaving expansions for other people to develop.

There are several ways to interface to external hardware, and with the 4 expansion ports, it should be possible to create an interface for any conceivable communications protocol. The best thing to do is going to be to focus on building expansion cards for serial and network communications. Of course, this can't really happen until we have a final design for the expansion ports, so this kind of thing is still a ways off.

The best thing to do for now is look at the memory map and the design of the existing system. I ask on FB about a pinout for the existing expansion connectors, but David said in his video that this might be changed to a different connector format. Regardless, knowing what bus lines are available on the expansion ports will help.

** update: reading the Programmer's Reference Manual, I don't think they're anywhere near ready to finalize an expansion bus connector format. In fact, they are still making architectural changes, as they recently moved the SD card interface and the system clock generator to VERA.
 
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Snd Exp

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Jan 9, 2020
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I watched the Dream Computer Part 2 video and the discussion around the sound hardware. Integration of FM synth hardware and a DAC seems certain. Good flexibility that all programmers would have access to from day one.

I did a bit of searching here but did not see someone talking about an on-board General MIDI synth. Or word it this way: Imagine effectively having a Roland MT-32 built into the system for what I think are a few dollars in parts. The beautiful sound of full wavetable synthesis (instruments plus a drum kit) without taxing the CPU by just a stream of serial commands feeding the synth IC. This would be in addition to the FM and DAC components previously discussed.

One solution to consider comes from the French company Dream and their SAM2695 IC.
  • 38-voice polyphony with effects
  • On-chip wavetable data
  • Analog line out for easy downstream mixing with the FM and DAC components
  • All-in-one design, QFN48 package
If something like this gets included in the design, there is a much higher likelihood that software will be written to take advantage of it. Examples of the past showed that the add-on nature of the MT-32 or the Gravis Ultrasound resulted in limited software support for what was superior audio at the time. I get excited to think of adding this sort of audio fidelity to the 8-bit nature of this machine. I can almost hear it in my head!

More information and sample schematics:
http://www.dream.fr/pdf/Serie2000/SAM_Datasheets/SAM2695.pdf
https://github.com/kinoshita-lab/MIDI-guy/blob/master/MIDI-Guy-schematics.pdf
https://www.dream.fr/other-documents.html
https://hackaday.com/tag/sam2695/

Thoughts?

-Tim
 
May 22, 2019
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I tend to agree... a MIDI synth would be nice to have. The only problem is I think it might stifle creativity in terms of "chiptune" sounds and music, since people would naturally gravitate toward the wavetable synthesizer, rather than the YM synth.
 

BruceMcF

Active Member
May 19, 2019
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I watched the Dream Computer Part 2 video and the discussion around the sound hardware. Integration of FM synth hardware and a DAC seems certain. Good flexibility that all programmers would have access to from day one.

I did a bit of searching here but did not see someone talking about an on-board General MIDI synth. Or word it this way: Imagine effectively having a Roland MT-32 built into the system for what I think are a few dollars in parts. The beautiful sound of full wavetable synthesis (instruments plus a drum kit) without taxing the CPU by just a stream of serial commands feeding the synth IC. This would be in addition to the FM and DAC components previously discussed.

One solution to consider comes from the French company Dream and their SAM2695 IC. ...

Thoughts?
When MIDI gets raised in the Facebook group, everything of course gets muddled ... since muddling things appears to be a primary function of Facebook ... but it tends to come down to:
(1) If you want it, that's what expansion cards are for; vs
(2) If it's included, that will maximize support for it.

Most of the design team do not seem to get involved in those discussions, and most of the interventions I recall tend to come down on the side of (1).
 

tpfaff100

New Member
Jan 20, 2020
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Something like a 12f629 but a little more powerful would host both MIDI and USB keyboard/mouse and feed data over SPI. Cost is probably $1 for the right chip. These things stand alone- just give them 5 volts, flash them with a program and they'll do what you want. They are true single chip computers!

This stuff has all been done before... someone might donate code. Would make a great add-in card.