Tachometer Sample

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Tachometer Sample
This sample demonstrates reading vehicle speed using tachometer inputs.
To run the sample:
1.
Download the sample code from https://github.com/Turta-io/RCDriverHAT/blob/master/Samples/Python/Tachometer.py​
2.
Copy the sample code to a folder on the Raspberry Pi.
3.
Open terminal, and then go to the folder you copied the sample.
4.
Run the sample with the following command:
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python3 Tachometer.py
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Sample Code
Tachometer.py
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#!/usr/bin/env python3
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​
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#This sample demonstrates reading vehicle speed using tachometer inputs.
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#Install RC Driver HAT library with "pip3 install turta-rcdriverhat"
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​
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from time import sleep
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from turta_rcdriverhat import Turta_RCDriver
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​
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#Initialize
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rc = Turta_RCDriver.RCDriver()
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​
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try:
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    #Activate fan at 50% speed
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    rc.set_fan(50)
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​
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    while True:
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        #Option one: Read both tach data in one shot
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        #Useful when you need all the readings within a minimal time
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        tach_all = rc.read_tachs()
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​
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        #Print the readings
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        if tach_all is not None:  #Check if data is received
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            print("Tach L....: " + str(tach_all[0]) + " rpm")
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            print("Tach R....: " + str(tach_all[1]) + " rpm")
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​
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        #Wait
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        sleep(1.0)
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​
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        #Option two: Read tachometer data one by one
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        #Useful when you need only one reading
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        tach_r = rc.read_tach(Turta_RCDriver.TACH_IN.RIGHT)
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​
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        #Print the reading
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        if tach_r is not None:  #Check if data is received
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            print("Tach R....: " + str(tach_r) + " rpm")
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​
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        #Wait
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        sleep(1.0)
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​
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        #Option three: Calculate speed as KMH
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        #Parameters: Ticks per revolution, Diamater in cm, MPH Output (Empty for KM/H)
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        speed_all = rc.read_tachs(1, 10)
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​
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        #Print the readings
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        if speed_all is not None:  #Check if data is received
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            print("Speed L...: " + str(speed_all[0]) + " km/h")
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            print("Speed R...: " + str(speed_all[1]) + " km/h")
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​
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        #Wait
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        sleep(1.0)
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​
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        #Option four: Calculate speed as MPH
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        #Parameters: Ticks per revolution, Diamater in cm, MPH Output (Empty for KM/H)
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        speed_all = rc.read_tachs(1, 10, True)
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​
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        #Print the readings
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        if speed_all is not None:  #Check if data is received
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            print("Speed L...: " + str(speed_all[0]) + " mph")
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            print("Speed R...: " + str(speed_all[1]) + " mph")
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​
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        #Wait
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        sleep(1.0)
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​
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#Exit on CTRL+C
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except KeyboardInterrupt:
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    print('Bye.')
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Result
When you run the sample, it reads RPM from the microcontroller. If there is valid data, it calculates speed accordingly. The example output should be like this:
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Tach L....: 0 rpm
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Tach R....: 0 rpm
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Tach R....: 0 rpm
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Speed L...: 0 km/h
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Speed R...: 0 km/h
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Speed L...: 0 mph
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Speed R...: 0 mph
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To stop the Python script, just press CTRL + C.
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