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:

python3 Tachometer.py

Sample Code

Tachometer.py

#!/usr/bin/env python3

#This sample demonstrates reading vehicle speed using tachometer inputs.
#Install RC Driver HAT library with "pip3 install turta-rcdriverhat"

from time import sleep
from turta_rcdriverhat import Turta_RCDriver

#Initialize
rc = Turta_RCDriver.RCDriver()

try:
    #Activate fan at 50% speed
    rc.set_fan(50)

    while True:
        #Option one: Read both tach data in one shot
        #Useful when you need all the readings within a minimal time
        tach_all = rc.read_tachs()

        #Print the readings
        if tach_all is not None:  #Check if data is received
            print("Tach L....: " + str(tach_all[0]) + " rpm")
            print("Tach R....: " + str(tach_all[1]) + " rpm")

        #Wait
        sleep(1.0)

        #Option two: Read tachometer data one by one
        #Useful when you need only one reading
        tach_r = rc.read_tach(Turta_RCDriver.TACH_IN.RIGHT)

        #Print the reading
        if tach_r is not None:  #Check if data is received
            print("Tach R....: " + str(tach_r) + " rpm")

        #Wait
        sleep(1.0)

        #Option three: Calculate speed as KMH
        #Parameters: Ticks per revolution, Diamater in cm, MPH Output (Empty for KM/H)
        speed_all = rc.read_tachs(1, 10)

        #Print the readings
        if speed_all is not None:  #Check if data is received
            print("Speed L...: " + str(speed_all[0]) + " km/h")
            print("Speed R...: " + str(speed_all[1]) + " km/h")

        #Wait
        sleep(1.0)

        #Option four: Calculate speed as MPH
        #Parameters: Ticks per revolution, Diamater in cm, MPH Output (Empty for KM/H)
        speed_all = rc.read_tachs(1, 10, True)

        #Print the readings
        if speed_all is not None:  #Check if data is received
            print("Speed L...: " + str(speed_all[0]) + " mph")
            print("Speed R...: " + str(speed_all[1]) + " mph")

        #Wait
        sleep(1.0)

#Exit on CTRL+C
except KeyboardInterrupt:
    print('Bye.')

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:

Tach L....: 0 rpm
Tach R....: 0 rpm
Tach R....: 0 rpm
Speed L...: 0 km/h
Speed R...: 0 km/h
Speed L...: 0 mph
Speed R...: 0 mph

To stop the Python script, just press CTRL + C.