Reading Arduino data directly into R
I have experimented with reading an Arduino signal into R in the past, using Rserve and Processing. Actually, it is much easier. I can read the output of my Arduino directly into R with the
Here is my temperature sensor example again:
And all it needs to read the signal into the R console with my computer is:
> f <- file("/dev/cu.usbmodem3a21", open="r") > scan(f, n=1) <b>Read 1 item</b>  20.8 > close(f)
Super simple: Open the file connection. Scan n lines of data. Close the file connection. Job done.Note: This worked for me on my Mac and I am sure it will work in a very similar way on a Linux box as well, but I am not so sure about Windows. Crucially, I had to learn the difference between the tty and cu devices. I found the following statement in Mike’s PBX Cookbook particular insightful:
You might notice that each serial device shows up twice in /dev, once as a tty.* and once as a cu.. So, what’s the difference? Well, TTY devices are for calling into UNIX systems, whereas CU (Call-Up) devices are for calling out from them (eg, modems). We want to call-out from our Mac, so /dev/cu. is the correct device to use.
You find the file address of your Arduino by opening the Arduino software and looking it up under the menu Tools > Port.
With a little more R code I can create a ‘live’ data stream plot of my Arduino.
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R version 3.1.2 (2014-10-31) Platform: x86_64-apple-darwin13.4.0 (64-bit) locale:  en_GB.UTF-8/en_GB.UTF-8/en_GB.UTF-8/C/en_GB.UTF-8/en_GB.UTF-8 attached base packages:  stats graphics grDevices utils datasets methods  base loaded via a namespace (and not attached):  tools_3.1.