USB MIDI using a PIC 18F2455

[joeman0613]

Dear All

It sounds the USB MIDI part of the project has been cancelled due to a silicon problem found on the EUSART of pic microcontrollers.

Is this issue now resolved with new pic silicon version ?

I would like to start the development of such MIDI USB project using a PIC18F2455.

Any chance to make it working ?

Thanks

J

[raphael]

Is this issue now resolved with new pic silicon version ?

Is there a new silicon version?

I've bought some 18F4550 last month and the bug still persists. AFAIK the bug isn't even mentioned in the erratas!

[joeman0613]

I'm not aware of any new silicon version.

BTW, are there any software workaround for the bugged silicon ?

What exactly is the problem ?

From what I read, it seems the problem comes from the UART which sends undesired byte "0", always ?

Are there bug on the USB as well ?

[stryd_one]

There are unconfirmed reports of software workarounds but they will have a negative performance impact and so are not practical for realtime use such as the MIDIBox. But then again that's not unusual for USB anyway ;)

Search the forums here and be sure to follow the link to the microchip website, and google for PIC18F EUSART bug. The answers you need are there (including the one above)

It doesn't send always, read around as above.

USB is done by the UART. Maybe you should google UART too :)

[joeman0613]

Thanks for your answers ...

So what is the solution ?

The EZ-USB AN2131 from cypress is obsolete now, it seems very difficult to order parts now, and the pic solution is not working !

How can we develop a USB MIDI bridge ?

Can I find the USB MIDI source code for the PIC available somewhere for download ?

I would be happy to have a look to this code, althrough it does not work due to the silicon issue .

Thanks

J

[Synapsys]

Hi J,

The silicon bug with the EUSART has not been corrected by Microsoft yet. The problem has been explained in threads here and on the Microchip forum. Back to back transfers are not possible since the TX port will transmit spurious bytes of all 0s. This makes it unacceptable for MIDI use.

However, do not dispair  :)

With the advent of the new IIC_MIDI project the Microchip USB is once again a viable alternative to the Cypress chip. Hang in there for a little longer.

Regards,

Synapsys

[ilmenator]

Sorry, couldn't resist, but this is a rather nice typo...

The silicon bug with the EUSART has not been corrected by Microsoft yet.

Though this time it's not Microsoft being the culprit...  ;D ...I had to look twice to see where the mistake in that sentence was ;).

Best , ilmenator

[TK.]

Yes, there is a workaround which is already working very nice - don't use the internal EUSART for MIDI Out, but external USARTs instead :)

Preview:

Can I find the USB MIDI source code for the PIC available somewhere for download ?

The firmware is currently only available for "known people", but I will release it sooner or later to the public.

Best Regards, Thorsten.

[joeman0613]

Thanks for the tips.

Anyway this will add extra cost to the project !

What reference of external UART do you currently use ?

Thanks

J

[raphael]

What reference of external UART do you currently use ?

I'm not Thorsten but AFAIK he uses the newly developed I2C-Midi module ;D

http://www.ucapps.de/mbhp_iic_midi.html

[joeman0613]

After some research, it seems the C8051F321 or C8051F320 from Silicon laboraties are a good alternative for USB MIDI bridges.

The chips are < $4 according to www.mouser.com

Timers, ADC, UART, USB, I2C, 16K Flash, 2K RAM

All we need !

In addition a complete dev kit with eval board + debugger is < $99

more infos here http://www.silabs.com/tgwWebApp/public/web_content/products/Microcontrollers/USB/en/USBMCU_matrix.htm

Anybody here is familiar with these MCU ?

Any comment, suggestion ?

[moebius]

Hmm..

I'm throwing a wild guess: those are 8051 derivates with higher clock speed and USB as a one additional interface. Or nothing new - as http://www.ucapps.de/mbhp_usb.html shows.

Moebius

[Nu-Audio-Science]

Great stuff TK, I noticed the IIC MIDI Module at Ucapps the other day and it looked cool.

[fergusnoble]

Hi,

There is a chip from FTDI called the FT232BM which is a USB to serial converter which supports many non standard baud rates, including 31250. Its is quite easy to use, i have used it on a number of other projects, but not as a MIDI interface (yet). I think they even hav a new version (the 232R?) which needs no external components, although i dont know if this one is available in a diy friendly package.

I think this would be a very simple solution to the problem, although it obviously provides only one MIDI port.

Cheers,

Fergus.

[moebius]

Hmm..

I'm throwing a wild guess: those are 8051 derivates with higher clock speed and USB as a one additional interface. Or nothing new - as http://www.ucapps.de/mbhp_usb.html shows.

Moebius  ;D