mrgeiger.py -- Mr. Geiger
Nick Parlante, 7/2012 Version 1.0
http://www-cs-faculty.stanford.edu/~nick/mrgeiger/

Mr. Geiger is a simple free program to process the output of the MightyOhm
geiger counter. The idea is that you can use the geiger counter
in a lab setting connected to a computer to record a series of measurements.
The program makes it easy to record data series suitable for
graphing or later processing.

Command line flags:

-i <input> -- *required*
 Using the very common FTDI serial chip, the input filenames look like:
  /dev/ttyUSB0 on Linux
  /dev/cu.usbserial-XXXXXXXX on the Mac
  Something like "com1" or "com2" on Windows
  
-o <output-file> -- write to named output file
-a -- auto output filename, e.g. 2012.04.01-23.14.12.csv (implies -o)
-e  -- echo the raw lines from the geiger counter
-g N -- group into samples of N seconds
        Output will be CSV format: seconds, count, cpm, uSv/hr
-t N -- timed exit after N seconds
-u X -- specify X as cpm to uSv/hr conversion factor

Use Ctrl-c to stop if not using -t N to exit.

**Example 1**
Group data by 20 seconds, ending at 120 seconds,
write the csv data to afile.csv as well as stdout:

mrgeiger.py -i /dev/cu.usbserial-A9007CPG -g 20 -t 120 -o afile.csv

seconds, count, cpm, uSv/hr
20, 6, 18, 0.1026
40, 7, 21, 0.1197
60, 4, 12, 0.0684
80, 9, 27, 0.1539
100, 11, 33, 0.1881
120, 8, 24, 0.1368
total seconds:120 count:45 cpm:22.5 uSv/hr:0.12825

In group -g 20 mode as show here, the cpm and other computations
just use the data in each 20 second group, not data from
any other time. The summary printed at the end uses the data
from the whole run.

**Example 2**
If -g group is not used, the output is left in the raw geiger format, e.g.
CPS, 0, CPM, 23, uSv/hr, 0.13, SLOW
and the summary stats are printed at the end of the run.
Here just analyze 90 seconds of data using -t 90:

mrgeiger.py -i /dev/cu.usbserial-A9007CPG -t 90

CPS, 0, CPM, 23, uSv/hr, 0.13, SLOW
CPS, 1, CPM, 24, uSv/hr, 0.13, SLOW
CPS, 0, CPM, 24, uSv/hr, 0.13, SLOW
CPS, 0, CPM, 24, uSv/hr, 0.13, SLOW
...more lines like this...
CPS, 1, CPM, 19, uSv/hr, 0.10, SLOW
CPS, 0, CPM, 19, uSv/hr, 0.10, SLOW
total seconds:90 count:26 cpm:17.3333 uSv/hr:0.0988

The raw data can be written to a file with: -o file.geiger
mrgeiger.py -i /dev/cu.usbserial-A9007CPG -t 90 -o file.geiger

A file like file.geiger can be used later with -i to process the raw data:
mrgeiger.py -i file.geiger -g 30

In this way, your can grab the raw data first and play around with
what -g options to process the data later.

See the following for sample data and graphs, and how to connect
and power Mighty Geiger from a cheap FTDI serial board.
http://www-cs-faculty.stanford.edu/~nick/geiger/

If a text line from the device looks wrong, an error is written
to stderr, and the line is skipped.
On the Mac, the 2nd data line is frequently garbled for some reason,
but everything else is fine. On Linux it seems to always work fine.

Bugs:

-The code does not set the baud etc. as that did not seem to be
necessary on any computer I tested it on.
I assume the FTDI chip is just happening to work in its default
configuration, but I don't know if that's a reliable solution.

-It only works when the geiger counter is in its "slow" once per second
mode, which should work for low and medium levels of radiation.

One could build a custom firmware for the Mighty Ohm Geiger, optimized
for this pure data-collection application. It could just report
only the raw count, say 10x per second, and let the higher level software
do all the data manipulation.