pyGPIO_2pin_km.py

from __future__ import division

import RPi.GPIO as GPIO
import datetime
import csv
import os
# import db_wrapper

# def upload_dropbox(results_file, fig):
#     db = db_wrapper.DropboxTerm()
#     print results_file
#     db.do_put(results_file, 'cvt_tests/'+results_file)
#     db.do_put(fig, 'cvt_tests/'+fig)

#setup the board layout
SPEDO_PIN = 18
TACH_PIN = 22

GPIO.setmode(GPIO.BOARD)
GPIO.setup(SPEDO_PIN, GPIO.IN)
GPIO.setup(TACH_PIN, GPIO.IN)

#initialize variables
spedo_state = GPIO.input(SPEDO_PIN)
tach_state = GPIO.input(TACH_PIN)
firstTime = lastUpdate = last_tach = last_spedo = datetime.datetime.now()
numberOfMagnets_spedo = numberOfMagnets_tach = 2
rpm_spedo = rpm_tach = averagedRPM_spedo = averagedRPM_tach = 0
alpha = .5 #filter constant

#setup csv stuff
f_name = "./cvt_test/CVT_Test_" + str(datetime.datetime.now()) + ".csv"
dataFile = open(f_name,'w+')
dataWriter = csv.writer(dataFile)
initMsg = 'Starting Test %d/%d/%d %d:%d:%2f' % (firstTime.day, firstTime.month, firstTime.year, firstTime.hour, firstTime.minute, firstTime.second+firstTime.microsecond/1000000.0)
dataWriter.writerow([initMsg])
# dataWriter.writerow(['Spedometer','Tachometer','Time since start'])

#main loop
while True:
    try:
        now = datetime.datetime.now()
        
        #SPEEDO
        #an edge of the magnet
        if GPIO.input(SPEDO_PIN) is not spedo_state:
            spedo_state = not spedo_state

            #a leading edge of the magnet
            if GPIO.input(SPEDO_PIN) is False:
                dt = max(1, (now - last_spedo).microseconds)/1000000.0
                rpm_spedo = 60.0 / numberOfMagnets_spedo / dt
                averagedRPM_spedo = averagedRPM_spedo*(1-alpha) + rpm_spedo*alpha
                last_spedo = now
    
        #catch the case when the input stops
        elif now - last_spedo > datetime.timedelta(seconds=0.25):
            print 'too slow'
            averagedRPM_spedo = max(1e-4,(averagedRPM_spedo) / 3)
            last_spedo = now

        #TACH
        #an edge of the magnet
        if GPIO.input(TACH_PIN) is not tach_state:
            tach_state = not tach_state

            #a leading edge of the magnet
            if GPIO.input(TACH_PIN) is False:
                dt = max(1, (now - last_tach).microseconds)/1000000.0
                rpm_tach = 60.0 / numberOfMagnets_tach / dt
                averagedRPM_tach = averagedRPM_tach*(1-alpha) + rpm_tach*alpha
                last_tach = now
    
        #catch the case when the input stops
        elif now - last_tach > datetime.timedelta(seconds=0.25):
            print 'too slow'
            averagedRPM_tach = max(1e-4,(averagedRPM_tach * 2) / 3)
            last_tach = now

        #print and log data
        if now - lastUpdate > datetime.timedelta(seconds=0.5):
            print "Spedo: %3f Tach: %3f" % (averagedRPM_spedo, averagedRPM_tach)
            if averagedRPM_tach > 0.01 or averagedRPM_spedo > 0.01:
                dataWriter.writerow([averagedRPM_spedo,averagedRPM_tach,round((now-firstTime).total_seconds(),1)])
                lastUpdate = now
            
    except (KeyboardInterrupt,SystemExit):
        print 'Shutting down...'
        dataWriter.writerow([])
        dataFile.close()

        #create plot png and upload csv and png to dropbox
        import cvt_test_mod as CVT
        fig = CVT.save_plot(f_name)
        # upload_dropbox(f_name, fig)
        # print "files uploaded"
        # os.remove(fig)
        break