DSS_sweeper_reader.py

#! /usr/bin/env python

# Read the output of an Arduino which may be printing sensor output,
# and at the same time, monitor the user's input and send it to the Arduino.
# See also
# http://www.arcfn.com/2009/06/arduino-sheevaplug-cool-hardware.html

import sys, serial, select
from time import sleep

class Arduino() :
    def run(self, baud=9600) :
        # Port may vary, so look for it:
        baseports = ['/dev/ttyUSB', '/dev/ttyACM']
        self.ser = None
        self.points = []
        for baseport in baseports :
            if self.ser : break
            for i in xrange(0, 8) :
                try :
                    port = baseport + str(i)
                    self.ser = serial.Serial(port, baud, timeout=1)
                    print "Opened", port
                    break
                except :
                    self.ser = None
                    pass

        if not self.ser :
            print "Couldn't open a serial port"
            sys.exit(1)
        self.ser.setDTR(False)
	sleep(1)
        self.ser.flushInput()
        self.ser.setDTR(True)
        while True :
            # Check whether the user has typed anything:
            inp, outp, err = select.select([sys.stdin, self.ser], [], [], .2)
            # Check for user input:
            if sys.stdin in inp :
                line = sys.stdin.readline().strip()
                if line == "wipe":
                    print "Clearing data"
                    self.points=[]
                self.ser.write(line)
            # check for Arduino output:
            if self.ser in inp :
                line = self.ser.readline().strip()
                print "Arduino:", line
                if line.count(',') == 4:
                    # must be a line with values
                    self.points.append((float(line.split(',')[0])/1000000,float(line.split(',')[2])/1000))
                if line == "End":
                    import matplotlib.pyplot as plt
                    plt.xlabel('FREQ')
                    plt.ylabel('VSWR')
                    plt.plot(*zip(*self.points))
                    plt.show()
                    

arduino = Arduino()
try :
    if len(sys.argv) > 1 :
        print "Using", sys.argv[1], "baud"
        arduino.run(baud=sys.argv[1])
    else :
        arduino.run()
except serial.SerialException :
    print "Disconnected (Serial exception)"
except IOError :
    print "Disconnected (I/O Error)"
except KeyboardInterrupt :
    print "Interrupt"