Created
April 29, 2021 22:31
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Hall Effect Tachometer - Rasberry Pi
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import time, datetime, sys | |
import RPi.GPIO as GPIO | |
sense_pin = 7 | |
LED_pin = 36 | |
GPIO.setmode(GPIO.BOARD) | |
GPIO.setup(sense_pin, GPIO.IN) | |
GPIO.setmode(LED_pin, GPIO.OUT) | |
last_time = time.time() | |
this_time = time.time() | |
RPM = 0 | |
def EventsPerTime(channel): | |
global RPM, this_time, last_time | |
GPIO.output(LED_pin, True) # LED on | |
this_time = time.time() # Get current real time | |
RPM = (1/(this_time - last_time)) * 60 # Revs/min real time diff | |
print('Current RPM = ', '{:7.1f}'.format(RPM)) # Instantaneous RPMs, not average | |
last_time = this_time # Store current time for next measurement; Requires multiple, contigious interrupts | |
GPIO.output(LED_pin, False) # LED off (flash when reading) | |
return() | |
# Interrupt: on input change, run EventsPerTime function | |
GPIO.add_event_detect(sense_pin, GPIO.RISING, callback=EventsPerTime, bouncetime=1) | |
# MAIN ROUTINE | |
timedate = datetime.datetime.now().strftime('%H:%M %Y%m%d %a') | |
print('System active @ ', timedate) | |
print('Ctrl-c to quit') | |
try: | |
for x in range(0, 1200): # Loop x times | |
time.sleep(0.5) # Time delay before looping | |
except: | |
time.sleep(2) # Allow settling before quitting | |
GPIO.output(LED_pin, False) | |
GPIO.remove_event_detect(sense_pin) | |
GPIO.cleanup() | |
print('Done') |
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