Got old toy rubbish you dont know where to put? Well bring to life again with Raspberry Pi and Pololu 1350 Micro Maestro 6-Channel USB Servo controller.
The idea is to replace the remote control receiver with Pololu Servo Controller, and drive it automously or manually via a remote web server.
This time we use python. Two things to attach: The front wheels drive, and the rear wheels engine. Communications is with Raspberry Pi is through USB Serial Port.
Please use the following code and figure out what needs to be modified in order to make a basic movement like forward left, backward, and stop.
import serial
import time
class ServoController:
def __init__(self):
usbPort = ‘/dev/ttyACM0’
self.sc = serial.Serial(usbPort)
def closeServo(self):
self.sc.close()
def setAngle(self, n, angle):
if angle > 180 or angle <0:
angle=90
byteone=int(254*angle/180)
bud=chr(0xFF)+chr(n)+chr(byteone)
self.sc.write(bud)
def setPosition(self, servo, position):
position = position * 4
poslo = (position & 0x7f)
poshi = (position >> 7) & 0x7f
chan = servo &0x7f
data = chr(0xaa) + chr(0x0c) + chr(0x04) + chr(chan) + chr(poslo) + chr(poshi)
self.sc.write(data)
def getPosition(self, servo):
chan = servo &0x7f
data = chr(0xaa) + chr(0x0c) + chr(0x10) + chr(chan)
self.sc.write(data)
w1 = ord(self.sc.read())
w2 = ord(self.sc.read())
return w1, w2
def getErrors(self):
data = chr(0xaa) + chr(0x0c) + chr(0x21)
self.sc.write(data)
w1 = ord(self.sc.read())
w2 = ord(self.sc.read())
return w1, w2
def triggerScript(self, subNumber):
data = chr(0xaa) + chr(0x0c) + chr(0x21) + chr(0x27) + chr(subNumber)
self.sc.write(data)
# MAIN
Maestro = ServoController()
iterations = 2
while(iterations > 0):
for chan in range(0,2):
for pos in range(0, 180):
Maestro.setAngle(chan, pos)
time.sleep(.002)
#print Maestro.getPosition(chan), Maestro.getErrors()
for chan in range(0,2):
for pos in range(180, 0, -1):
Maestro.setAngle(chan, pos)
time.sleep(.002)
#print Maestro.getPosition(chan)
e1, e2 = Maestro.getErrors()
if e1 != 0 or e2 != 0:
print e1, e2
break
iterations = iterations – 1
print “Trigger Script”
Maestro.triggerScript(0)
time.sleep(2)
Maestro.closeServo()
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