#Explorer HAT Pro, Motors, Servos and Steppers
Find this Gist at: tiny.cc/explorerhat
The Motor driver on Explorer HAT Pro can not only drive motors, but a stepper motor too. And just like the Pibrella the outputs can also drive a motor or four, or another stepper.
Explorer HATs outputs sink to ground, meaning that you need to connect whatever you're driving between 5V and the output
#MOTORS
Driving a motor with Explorer HAT is easy, you just import the library:
import explorerhatHook up a motor to channel 1 or 2, and tell it to go forward, backward or stop:
explorerhat.motor.two.forward()
explorerhat.motor.two.backward()
explorerhat.motor.two.stop()#STEPPERS
Steppers are a little trickier. We're using 28BYJ-48 steppers and they need a "step sequence" in order to function. It also helps to ramp up their speed from a slow sequence to a gradually faster one.
Connect the stepper as follows:
- Red Wire -> 5V
- Yellow Wire -> Output 1
- Orange Wire -> Output 2
- Pink Wire -> Output 3
- Blue Wire -> Output 4
The following code will now run through the step sequene and drive the stepper using Explorer HAT's outputs:
#!/usr/bin/env python
import explorerhat, time
sleep_time = 0.1
min_sleep = 0.001
step_sequence = [
[0,1,0,0],
[1,1,0,0],
[1,0,0,0],
[1,0,1,0],
[0,0,1,0],
[0,0,1,1],
[0,0,0,1],
[0,1,0,1]
]
while True:
for step in step_sequence:
for pin in range(4):
explorerhat.output[pin].write(step[pin])
time.sleep(sleep_time)
if sleep_time > min_sleep:
sleep_time /= 1.1#SERVOS
Driving a servo or two is a little more complicated and requires the use of Pi-blaster: https://github.com/sarfata/pi-blaster
After following the install instructions and running pi-blaster as root, you can control a servo connected to GPIO 18 ( marked PWM on Explorer HAT ) by writing:
echo 18=0.2 > /dev/pi-blasterIn the terminal.
The file /dev/pi-blaster is a FIFO- it's a shared buffer that lets you send commands to pi-blaster from other programs.
To control servos from Python, you need to "open" this FIFO in Python and write commands to it, like so:
servo = open('/dev/pi-blaster')
f.write('18=0.3\n')
f.flush()
please put line spaces between Red Wire -> 5V Yellow Wire -> Output 1 Orange Wire -> Output 2 Pink Wire -> Output 3 Blue Wire -> Output 4
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