[Rd] Serial connections?

[shotwelm]

I've done some microcontroller work over serial also. Unfortunately,
interfacing with a serial port is system dependent, and the mechanisms
can be quite different, as you probably know. It appears that Simon has
a solution below that will work if you are willing to accept the default
baud rate (9600 is way too slow for good sensor data), parity, etc.. or
use external tools. On POSIX systems, you would need access to the
termios.h header and the system ioctl function in order to change these
settings. Although I'm not 100% sure, I don't think R has this
capability ... yet. 

I'm new to the list, but I'd be surprised if the R developers that have
been around awhile haven't already considered adding support for ioctls
and the POSIX terminal interface. This makes me wonder why it's not
there. If there is no good reason, I'm starting to see a series of R
packages (or core extensions) developing. With a package for ioctls, we
could use all sorts of cool stuff, like Video4Linux2 (webcams, HAM
radio, tuners)...

When I collect sensor data over serial, I do it in python or write a
small C program to dump a single-column csv. Of course, R is excellent
for digital signal processing after that. Check out the DSP
( http://biostatmatt.com/archives/78 ) I did in R with some ECG data I
collected with an Atmel uC. 

-Matt


On Tue, 2010-04-20 at 11:05 -0400, Simon Urbanek wrote:
> On Apr 20, 2010, at 10:33 AM, Blair Christian wrote:
> 
> > Does anybody know if there is any support to read from serial ports? I just got an arduino, and wanted to write some scripts for working with real time streaming sensor data...
> > 
> 
> Yes (I have Arduinos reporting measurements from all sensors in the house to R on my iMac which produces plots that are synchronized with my webserver). In principle you can simply use /dev/tty.usb... and read from it. In most cases the default setting is already fine (9600,n,8,1 on Mac) or you can use tools the set it up in advance (setserial on Linux etc.) so you don't have to worry about setting up the serial from R.
> 
> Depending on your OS you may be able to read from the serial device directly with a regular file connection or you can use a pipe connection to a tool which pipes out from the tty to stdout (written for a Mac but may work on other unices):
> 
> https://svn.rforge.net/C/trunk/tools/ttys.c
> 
> and then use something like
> 
> f=pipe("ttys /dev/tty.usbserial-X1234")
> 
> A rather handy option -d prepends current time to each line so you can track output over time. I have some more tools for this (even allowing you to share form Arduino output with several computers or even send remote commands to your Arduino including encryption etc ...).
> 
> Cheers,
> Simon
> 
> PS: From experience I can say that Arduinos are highly addictive so beware ;).
> 
> 
> > In base::connections documentation, it's not clear if there's an easy
> > way to do this?  Any ideas on hacking it?  I'm open to win/linux/mac
> > solutions.  I'm not sure how sockets work, but possibly there is a way
> > to pipe things to a buffer and read from a buffer in bash (in my linux
> > mind I have the thought of trying to redirect /dev/something to a
> > file, or symlinking a file to point to the hardware, but know that
> > there has to be some secret sauce to go from streaming in to a
> > readable file, but don't know what the missing components are).
> > 
> > Thoughts?
> > 
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> > 
> > 
> 
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