arduino-sa.py

#!/usr/bin/python2.7
""" Client utility for the Arduino Spectrum Analyzer as found on github:
https://github.com/frack/Arduino-SpectrumAnalyzer
More information on how to build this device:
http://frack.nl/wiki/Arduino_Spectrum_Analyzer """
_author__ = 'Rudi Daemen <fludizz@gmail.com>'
__version__ = '0.3'

# Wifi|    Frequency (MHz)
# Chn | Center | Start | End
#  1  | 2412   | 2402  | 2422
#  2  | 2417   | 2407  | 2427
#  3  | 2422   | 2412  | 2432
#  4  | 2427   | 2417  | 2437
#  5  | 2432   | 2422  | 2442
#  6  | 2437   | 2427  | 2447
#  7  | 2442   | 2432  | 2452
#  8  | 2447   | 2437  | 2457
#  9  | 2452   | 2442  | 2462
#  10 | 2457   | 2447  | 2467
#  11 | 2462   | 2452  | 2472
#  12 | 2467   | 2457  | 2477
#  13 | 2472   | 2462  | 2482
#  14 | 2484   | 2474  | 2494

import serial
import time
import sys
import optparse
import matplotlib.pyplot as plt
try:
    import json
except ImportError:
    import simplejson as json


def ArduinoSerial(device='ttyUSB0', baud=57600):
  """ This function Opens the arduino, resets the device by sending a DTR signal
  and then checks if it is an Arduino Spectrum Analyzer. If all goes well, it
  returns the serial connection object. """
  arsa = serial.Serial(device, baud, timeout=10)
  arsa.setDTR(True)
  arsa.setDTR(False)
  arsa.readline()
  if "ArduinoSA" in json.loads(arsa.readline()):
    return arsa
  else:
    raise Exception('Device is not an ArduinoSA!')


def ReadSingleSweep(arsa):
  """ Returns a dictionary with 100 measurements. Each single measurement is a
  1MHz channel as key with it's RSSI as corresponding value. """
  print "%s: Starting sweep..." % time.asctime()
  while True:
    data = arsa.readline().strip()
    try: 
      return json.loads(data)["ArduinoSA"]
    except ValueError:
      print 'ValueError! Unable to read data. Resetting device ...'
      arsa.setDTR(True)
      arsa.setDTR(False)
      arsa.readline()

def PlotSomeStuff(device='/dev/ttyUSB0', baud=57600):
  """ Uses ReadSingleSweep to build up individual graph data and plots
  it to the screen. It leaves a ghost graph for previous values. """
  arsa = ArduinoSerial(device, baud)
  plt.ion()
  x2 = y2 = None
  while True:
    x = []
    y = []
    for items in ReadSingleSweep(arsa):
      x.append(items["freq"])
      y.append(items["rssi"])
    plt.clf()
    if x2 and y2:
      plt.plot(x,y,'r-', x2,y2,'r:')
    else:
      plt.plot(x,y, 'r-')
    plt.ylim((0, 35))
    plt.grid(True, which='major', axis='both')
    plt.ylabel('RSSI')
    plt.xlabel('Frequency')
    plt.draw()
    x2 = x
    y2 = y



if __name__ == '__main__':
  usage = "usage: %prog [options]"
  parser = optparse.OptionParser(usage=usage)
  parser.add_option("-d", "--device", metavar="DEVICE", default="/dev/ttyUSB0",
                    help="The serial device the Arduino is connected to.")
  parser.add_option("-b", "--baud", metavar="BAUD", default=57600, type="int",
                    help="Baudrate at which the Arduino is communicating.")
  (opts, args) = parser.parse_args()
  try:
    print "%s: Unrecognized argument \'%s\'" % (sys.argv[0], args[0])
    print "Try \'%s --help\' for more information." % sys.argv[0]
    sys.exit(1)
  except IndexError:
    pass
  print "Using device %s at %i baud..." % (opts.device, opts.baud)
  try:
    PlotSomeStuff(opts.device, opts.baud)
  except KeyboardInterrupt:
    sys.exit("KeyboardInterrupt - Bye bye!")