Baud rate with FT232RL USB board

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Baud rate with FT232RL USB board

Postby yorkiebars » Fri Dec 28, 2007 1:33 am

Hi everyone,

I am an electronic engineer, and in my spare time, a drummer, pianist and music producer, so naturally i think MegaDrum looks cool.

Hopefully someone can help me with the following questions:

When you use the FT232RL USB board with the Roland or Kawai midi-over-serial drivers, is the ft232 ic running at the 31250 midi baud rate(which i know it should support, unlike normal 16550-based com ports)? Or does the firmware on the ATmega device have to be changed to make its serial interface operate at 38400 baud?

Also, have there been any problems getting the midi drivers to recognise ftdi's virtual com port?

The reason i ask is that i am thinking of using the ft232 in a midi project of my own. Any advice is much appreciated.

yorkiebars
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Re: Baud rate with FT232RL USB board

Postby Synthex » Fri Dec 28, 2007 1:58 pm

Why not use the 18F2550 which makes a real MIDI interface ? ;)
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Re: Baud rate with FT232RL USB board

Postby yorkiebars » Fri Dec 28, 2007 5:13 pm

well i could use your PIC solution of course, but i'd still like to know if anyone has the answer my original question.
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Re: Baud rate with FT232RL USB board

Postby Synthex » Fri Dec 28, 2007 5:29 pm

yorkiebars wrote:When you use the FT232RL USB board with the Roland or Kawai midi-over-serial drivers, is the ft232 ic running at the 31250 midi baud rate(which i know it should support, unlike normal 16550-based com ports)? Or does the firmware on the ATmega device have to be changed to make its serial interface operate at 38400 baud?

The ATmega device operates at 38400 baud.
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Re: Baud rate with FT232RL USB board

Postby yorkiebars » Fri Dec 28, 2007 5:43 pm

Thanks. I have just read application note AN232B-05 from ftdi which says you can "alias" one baud rate with another by modifying ftdiport.inf such that when the software asks for 38.4 kbps then you actually get 31.25 kbps, so i conclude it would be possible.

So if the ATmega's USART is always at 38.4 kbps with the megadrum firmware then surely your PIC is too, and midi over the DIN plugs wouldn't work (as they are in parallel)? I'm confused.
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Re: Baud rate with FT232RL USB board

Postby Synthex » Fri Dec 28, 2007 5:53 pm

yorkiebars wrote:So if the ATmega's USART is always at 38.4 kbps with the megadrum firmware then surely your PIC is too, and midi over the DIN plugs wouldn't work (as they are in parallel)? I'm confused.

My PIC solution works with 31.25 kbps only, it's a real midi interface.
The ATmega's USART is not always at 38.4 kbps. You can choose it by menu :
- 38.4 kbps for Atmega8 or ft232, then DIN midi output and input don't work.
- 31.25 kbps for PIC and real DIN midi output and input.
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Re: Baud rate with FT232RL USB board

Postby yorkiebars » Fri Dec 28, 2007 6:25 pm

That makes sense. What i am planning to do is to take a Waveblaster-compatible tone generator board, which has a TTL midi in, then give it its own power supply and a usb interface rather than an optoisolator and din socket, so i don't have to use up an actual midi interface to connect it to my PC.
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