usb driver problem

Thomas McGrath III mcgrath3 at
Sun Jan 23 09:31:49 EST 2011


Thank you for this. I am going to focus on these settings you describe. Especially after reading Jerry's primer I think you both are right and this is where to start.

Yes, the Arduino can and does work well from the Terminal "screen" program. Also from 'many' downloaded serial reader/monitor applications I have found and downloaded to test this.

To complicate things further there are actually two(*) ways to use the Arduino Uno over serial connections:
(1.) The Uno comes with the Atmega8U2 which handles the Serial to USB conversion on the chip on the board (the Make board used the older FTDI method). This (Atmega8U2) is the method used for downloading sketches to and communicating with the Arduino Uno from Processing, Serial Monitor, and the Arduino IDE. 

(2.) The second method is using some of the pins on the Arduino for UART TTL (5V) Serial Communication. When you use pins 0 (RX) and 1 (TX) and #include the softwareSerial library You can in effect have two serial ports to the Arduino at the same time. The is useful if as in my case you want to use one serial port on the Computer to connect/monitor/control the Arduino Uno and use the other serial connection to connect to another serial device like the Roomba.

 (((Yes, I am building a fully autonomous lawnmower robot based on the Roomba routines with outside logic from the Arduino which will also include an OSC controller and be accessed from an iPhone. I want to be able to LC on the iPhone/Desktop instead of another OSC controller and Mark has already written the wonderful OSC library in his Make Board Controller to use.)))

NOTE: It is my bet that using the pins and the softwareSerial library MOST emulates the 'old' way (FTDI) of doing serial communications with the Arduino and would probably work as expected in LC. ( I have to dig up some old serial cables and splice them for connecting and then dig out my old Keyspan High Speed Serial Converter WITH driver). But I didn't want to confuse things from the start. It would however be better to just be able to plug in with the straight USB cable that comes with the Arduino Uno and figure out what settings on the LC side will make this work. After all it does work with Terminal and a dozen other apps.

* Actually there are many many more ways to connect not limited to but including Bluetooth, Wifi, Ethernet, IR, Radio, etc.


-- Tom McGrath III
3mcgrath at

On Jan 23, 2011, at 2:34 AM, Mark Wieder wrote:

> Jerry-
> Very nice writeup.
> Tom-
> Given that you're using an emulated serial port, my guess is that you
> won't have to fiddle with the handshaking lines. This is where a usb
> breakout box would really come in handy. But depending on the
> emulation, some of the things that might affect buffering would be the
> odsr, octs, dtr, and rts lines. So I'd try something like this (watch
> the line wraps):
> set the serialControlString to "baud=9600 parity=n data=8 stop=1
> odsr=on octs=on odtr=on orts=on"
> Do note that if you need to set the serialControlString, rev will
> *reset* the serial port before applying your settings. This is
> annoying, counterproductive, and needless, but that's the way it is.
> It's caused me to rule out rev for solutions before.
> Can you talk to the Arduino from a terminal window?
> -- 
> -Mark Wieder
> mwieder at
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