MIDI Decoder Chip?

Is there an IC that will decode MIDI data? I need something that I can use in an embedded system with a fairly simple (e.g. 8051 or PIC) microcontroller. Ideally the chip would take MIDI data directly and output analog audio for an amplifier, run on 5V and be available retail in a thru hole package, but I'll take what I can get :-) It does have to be something I can by retail, though, in small quantities.

I know there are MP3 decoder chips (e.g. the STA013) that approach this ideal, but I really need to play MIDIs, not MP3s.

Thanks, Bob Armstrong

Reply to
bob
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i say either a basic synthesiser chip, or read the midi spec farther than the first half page. try midi fanatics brainwashing center, it'll probably help you.

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Reply to
jim dorey

MIDI Is a standard of controls and notes. It does not dictate instrumentation. MIDI Is like having the sheet music to a song. It has no inherent sound. What you need is a sound synthesizer that understands MIDI and can generates sound based upon it.

There is a standard called "General MIDI" which puts specific instruments on specific channels and patches, but you really need to understand what your MIDI source is set up for to know what it's going to play. I have MIDI files I've created from my own sequences, but you can't play them back on anything other than my studio (no sounds will be correct).

-->Neil

Reply to
Neil Bradley

Yes, It's called an UART.

Practically all microcontrollers have at least one UART built in, so you're not likely to need anything but your microcontroller and an electrical interface for the 5 ma current loop (use e.g. a 6N138 optocoupler).

DJ

Reply to
Dr Justice

I think you completely misunderstand what MIDI is. MIDI is just the information a MIDI keyboard generates when you play it - i.e. note on, note off information and things like the continuous data output of a pitchbend wheel. It is "button press" information, not audio. Put this information into a MIDI equipped sound module and then you will get sound.

If you want to receive this information with something like an 8051 it is quite easy using some buffering/opto-isolator circuitry. Search the web for this, there is loads of information. You will also find various MIDI routines you can use or adapt, depending on what you want to do with the information.

Gareth.

Reply to
Gareth Magennis

I'm sorry for not being clear, but you guys misunderstand - I don't want to control an external MIDI synthesizer. I want a MIDI synthesizer chip that I can build into a project.

Think of a cell phone - most phones these days can render MIDI ring tones. I need something on that level.

Yes, I know that many MIDIs will end up sounding like cheap elevator music (or a cell phone!) when rendered this way, but that's OK.

Thanks, Bob

Reply to
bob

P.S. Something like the Micronas MAS3505G is an example of what I'm talking about

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EXCEPT a) I don't know of any retail source for this chip in unit quantities, and b) it's only available in a BGA package which I couldn't solder even if I had one!

Thanks again, Bob

Reply to
bob

In article , " snipped-for-privacy@jfcl.com" writes

Winbond do one, W56964 which is a 34 pin QFP, general midi synth including a power amp, but I have no idea where you would obtain them in small quantities.

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Tim Mitchell
Reply to
Tim Mitchell

I found these chips that are still in manageable DIP/SOP packages:

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Not sure if they have distributors where you are.

/Rolf

Reply to
Rolf Blom

Well, suffice it say it might have helped if you had asekd for a synthesizer chip right away, instead of speaking about a "decoder" chip. Acquiring anything like that in qty less than 1000 might indeed prove challenging, these days, when most applications, including cellphones, would just use a DSP and a huge wave table memory instead of dedicated chips.

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Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.
Reply to
Hans-Bernhard Broeker

DSP is an overkill. UART is unnecessary. Just use a DIP micro with timer/counter. You can just program it to change the tone/frequency every few msec. However, you do need lots of external data storage for the wave table. If I were you, I would use an 40 pins DIP AVR hooking up to a Compact Flash. If you need it, I can send you a simple layout for it. The rest is just software.

Reply to
linnix

"linnix" schreef in bericht news: snipped-for-privacy@z14g2000cwz.googlegroups.com...

'Just software' sounds like software is easy/trivial and hardware is difficult while it's the other way round.

Jeroen

Reply to
Jeroen

Both hardware and software are relatively easy. You can probably wire-wrap a board in a few hours. Take a ATmega 16 (40 pins dip) AVR. Hook up one of the Port A PWM output to a low-pass filter (RC) and speaker. Port B & D to the Compact Flash data bits. Port C to the control bits.

Setup time 1 to output PWM tones and time 2 for the durations. Keep feeding the timers from the Compact Flash wave table.

Should cost less than $20 dollars total.

Reply to
linnix

If you really don't want to implement the synth in software, I think maybe the really old soundblaster-type cards had a midi synth chip of some sort that you might be able to desolder and re-use (you want something before the board went to being just one asic). You'd probably have to have a micro to get the data between the actual midi interface and the chip, since it's probably expecting to be fed over the ISA bus.

Oh, the old chip will no doubt sound terrible since it will use FM synthesis rather than a wavetable. But then homebrew software might not sound so great either.

On the positive side, big flash devices are fairly cheap now, so wavetables are practical in a microcontroller implementation. You might want to use a DSP-flavored micro with lots of helpful instructions and a hardware interface to common serial audio DAC's.

Reply to
cs_posting

You might try Yamaha. They used to have a range of synthasizer chips which might still be in production. There might be an obscure Far Eastern second source which still produces the devices for niche markets. People in the retro-computer scene might be able to help. (Old Ataris, Commodores etc. often had add-ons that contained these synthesizer chips)

Regards Anton Erasmus

Reply to
Anton Erasmus

Do these chips actually accept MIDI commands directly? The chips I recall from years (okay, decades) ago were parallel-interface peripherals for a microprocessor bus (such as the C64's SID chip and earlier GI AY-3-whatever used in arcade video games). These used the computer's main processor to decode the MIDI commands and put the proper values into the sound chip's registers. I suspect even in a cell phone the MIDI rendering is in software. There was at least one hardware implementation of MIDI (Roland TR-707 drum machine used lots of CMOS logic), but with MIDI-capable microcontrollers for a dollar or less, it only makes sense to use one. There's also exactly how much MIDI functionality you want. The original MIDI spec is just receiving note-on and note-off commands, and playing and stopping each note as the appropriate command is received, but there's also MIDI File Format, where you have a file (under most OS's, the extension is .MID) that has a whole song (note-on's and note-off's, but also the timing between these is encoded in the file), you would send the file to the chip and tell it to play (presuming such a chip exists). The point is that something may say it "does MIDI" and be technically true, but it may not do everything you expect.

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Reply to
Ben Bradley

I am not sure. It has been years since I have read any of the datasheets, or looked at these devices. There were a few fairly complex devices available since the CPUs used as the main CPU were not that fast.

Regards Anton Erasmus

Reply to
Anton Erasmus

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