What is the fastest way to make a microcontroller interact with a computer over USB?

Question

I'm trying to build a usb MIDI controller for interfacing with audio software using AVRs.

But I found that you can let the AVR interface with the USB without any other chips or that you

can use ftdi chips.

Are these the only 2 ways? And if so, wich one is the fastest?

If someone also thinks that AVR is not the way to go for this, please let me know.

Thanks in advance guys!

dougw · Accepted Answer

Hi Felix,

The PSoC4 module has USB, but it is not native to the PSoC4 chip, so it adds a minor delay - probably insignificant.

There is also a PSoC5 prototyping kit (faster and more powerful) with native USB - cost about $10.

Arduino Pro Micro also has built-in USB (ATmega32U4) for about the same cost.

The PSoC5 (ARM Cortex M3) is way faster and more powerful.

The Pro Mirco is a smaller module.

For MIDI I use a low cost MIDI - USB cable (~$5)

I gather it introduces about 1 ms of latency, but I certainly can't tell - the latency in my system is dominated by sound processing, not MIDI conversion.

Doug

shabaz · Answer

You can't go faster than the USB specs, see the Wikipedia page for the bit rates. And you can't process data faster than the speed of your processor - an AVR is not particularly fast. I don't think MIDI is particularly fast either (31250 baud) but clearly way slower than the AVR, so I don't get the question I'm afraid.

michaelkellett · Answer

There is a standard for Midi over USB and I doubt that an ATTiny can support it. Think about getting a processor with a full USB port implemented in hardware. Do some serious Google trawling and you might well find some code for an ARM based solution.

Start here:

https://en.wikipedia.org/wiki/MIDI#USB_and_FireWire

Then Google 'midi over usb' and expect to do some reading (lots).

MK

What is the fastest way to make a microcontroller interact with a computer over USB?

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