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Topic: serial speeds (Read 1 time) previous topic - next topic


It would be great to have the possible serial speeds listed in the html reference docs...


I added a list to the Serial.begin() docs: http://www.arduino.cc/en/Serial/Begin

I hope they're right.  


Jan 18, 2007, 10:37 am Last Edit: Jan 18, 2007, 10:38 am by Daniel Reason: 1
Excellent intercontinental response time!




I can't still push it above 38400 without getting bogus chars...
is there a hardware limitation somewhere?
is my old arduino usb not built for those higher speeds?



Huh.  It might be a problem with the old board.  Higher speeds work fine on the NG.  Maybe Massimo knows more?


Hi Mellis,

i'm looking for an easier way to get midi data from my arduino inside my mac than using a midiman adapter cable.

since AVR-USB  seems out of range for my current project (http://forums.obdev.at/viewtopic.php?p=679#679), i'm trying to get things working with some kind of serial-to-midi software solution.

i tried to "hack" the ftdi driver to allow a baud rate of 31500.
see http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1161023163/0
my problem is that i cannot confirm hack since no serial port application like zterm allows that baudrate.

would it be possible to have the serial monitor in the arduino IDE support this baud rate?
can this be done by changing some pref file or would it need a recompile?

best, kuk


You could try using Processing.

Does your hack work the same way as the Windows one (i.e. mapping 38400 to 31500)?  If so, then I think you just need a program that accepts 38400 baud, even though the Arduino is really running at 31500.  

I'm not sure what you gain by getting the driver to work at 31500 though.  Do you have a program that will read MIDI data if it's coming in over a serial port at that speed?  


it's 31.250 for Midi of course,  ::)

yes, it's supposed to be the "same hack" as on a pc. but without getting it to work yet.

that's what i wanted the serial monitor for. i just wanted to know that the serial speed (the driver hack) works...

the next thing would be to add serial to midi translation.

did you hardcode the serial speeds into the arduino IDE or do they come from the operation system? i really wonder why i can't seem to find a mac application with non-standard speeds.

thanks for the reply,



If your hack works the same way as the Windows one, you should be able to tell the application to open the serial port at 38400 baud and the driver will actually communicate at 31500.  Does it not work that way?

The baud rates in the Arduino serial monitor are hard-coded, so you'd have to recompile the environment to change them.  


Thanks for the reply,

i think i'm not quite there yet. it _should_ work like the pc-hack. but i didn't really understand the concept of aliasing baud rates. hope it'll work with the mac driver. all ftdi documentation seems to deal with .inf files.

i'll get into this after the weekend. this gives me enough hope for another try at least.

The Cat Herder

I'm also using the arduino for midi development. I've run into the same issue with the serial monitor. It would be great if 31250 was an option for serial speed.


Can you explain a bit more?  You've got the Arduino board communicating with the computer at 31250 baud and you'd like to be able to view this communication with the serial monitor?  

Out of curiosity, what program are you using to receive the MIDI data from the board?  How did you get it to recognize data coming over the serial port?

The Cat Herder

My current project involves using the Arduino to send midi messages to control a hardware audio effects processor. Most effects processors allow you to change settings through midi messages. I have the Arduino communicating at 31250 baud, which is the speed used by midi. These messages are then sent out via a midi connector.
The serial monitor would be used more as a development aid, as opposed to a final implementation. That way I wouldn't have to have the midi jack hooked up to the board or the corresponding hardware while I'm developing. My posting was mainly in response to the posting by: mellis
The baud rates in the Arduino serial monitor are hard-coded, so you'd have to recompile the environment to change them.

Perhaps support for 31250 in the serial monitor could be included in the next release.


Thanks for explaining.  It's certainly easy enough to add to the list, now that I understand why it's wanted.  I'll have to test that the driver can actually communicate at that speed though.


Unfortunately, it seems that the library we're using for serial communication (RXTX) doesn't support 31250 as a baud rate, so this won't make it into Arduino any time soon.  I'm afraid I don't really know enough about USB/serial communication to know how difficult it is to work around this.

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