Test of the H-Bridge Block with the Intel Edison

edison_h-bridge_test.py

import mraa
import time

# Motor parameters. Set to 1 or -1 to change default direction
dirA = 1
dirB = 1

# PWM A (pin 12) is on pin 20 in MRAA
pwmA = mraa.Pwm(20)
pwmA.period_us(1000)
pwmA.enable(True)

# PWM B (pin 13) is on pin 14 in MRAA
pwmB = mraa.Pwm(14)
pwmB.period_us(1000)
pwmB.enable(True)

# Direction pins A1 and A2 are on GPIO 48 and 47 (33 and 46 in MRAA)
a1 = mraa.Gpio(33)
a1.dir(mraa.DIR_OUT)
a1.write(1)
a2 = mraa.Gpio(46)
a2.dir(mraa.DIR_OUT)
a2.write(1)

# Direction pins B1 and B2 are on GPIO 15 and 14 (48 and 36 in MRAA)
b1 = mraa.Gpio(48)
b1.dir(mraa.DIR_OUT)
b1.write(1)
b2 = mraa.Gpio(36)
b2.dir(mraa.DIR_OUT)
b2.write(1)

# Standby pin is GPIO 49 (47 in MRAA)
standby = mraa.Gpio(47)
standby.dir(mraa.DIR_OUT)
standby.write(1)

# Put the motor driver into standby mode
def standby(mode):
    if standby:
        standby.write(0)
    else:
        standby.write(1)

# Differential drive. A and B can be -1 to 1.
def diffDrive(speedA, speedB):

    # Make sure the speeds are within the bounds
    if speedA < -1.0:
        speedA = -1.0
    if speedA > 1.0:
        speedA = 1.0
    if speedB < -1.0:
        speedB = -1.0
    if speedB > 1.0:
        speedB = 1.0

    # Set motor speeds
    speedA = dirA * speedA
    speedB = dirB * speedB
    if speedA < 0:
         a1.write(0)
         a2.write(1)
         pwmA.write(abs(speedA))
    else:
        a1.write(1)
        a2.write(0)
        pwmA.write(speedA)
    if speedB < 0:
        b1.write(0)
        b2.write(1)
        pwmB.write(abs(speedB))
    else:
        b1.write(1)
        b2.write(0)
        pwmB.write(speedB)

# Test
diffDrive(1.0, 1.0)
time.sleep(1.0)
diffDrive(0.0, 0.6)
time.sleep(1.0)
diffDrive(-0.8, 0.8)
time.sleep(1.0)
diffDrive(-0.7, -0.7)
time.sleep(1.0)
diffDrive(0.0, 0.0)