I2C fix plus PWM support

Author: K. Townsend

Adafruit_PWM_Servo_Driver/Adafruit_PWM_Servo_Driver.py

@@ -0,0 +1,67 @@
+#!/usr/bin/python
+
+import time
+import math
+from Adafruit_I2C import Adafruit_I2C
+
+# ============================================================================
+# Adafruit PCA9685 16-Channel PWM Servo Driver
+# ============================================================================
+
+class PWM :
+  i2c = None
+
+  # Registers/etc.
+  __SUBADR1            = 0x02
+  __SUBADR2            = 0x03
+  __SUBADR3            = 0x04
+  __MODE1              = 0x00
+  __PRESCALE           = 0xFE
+  __LED0_ON_L          = 0x06
+  __LED0_ON_H          = 0x07
+  __LED0_OFF_L         = 0x08
+  __LED0_OFF_H         = 0x09
+  __ALLLED_ON_L        = 0xFA
+  __ALLLED_ON_H        = 0xFB
+  __ALLLED_OFF_L       = 0xFC
+  __ALLLED_OFF_H       = 0xFD
+
+  def __init__(self, address=0x40, debug=False):
+    self.i2c = Adafruit_I2C(address)
+    self.address = address
+    self.debug = debug
+    if (self.debug):
+      print "Reseting PCA9685"
+    self.i2c.write8(self.__MODE1, 0x00)
+
+  def setPWMFreq(self, freq):
+    "Sets the PWM frequency"
+    prescaleval = 25000000.0    # 25MHz
+    prescaleval /= 4096.0       # 12-bit
+    prescaleval /= float(freq)
+    prescaleval -= 1.0
+    if (self.debug):
+      print "Setting PWM frequency to %d Hz" % freq
+      print "Estimated pre-scale: %d" % prescaleval
+    prescale = math.floor(prescaleval + 0.5)
+    if (self.debug):
+      print "Final pre-scale: %d" % prescale
+
+    oldmode = self.i2c.readU8(self.__MODE1);
+    newmode = (oldmode & 0x7F) | 0x10             # sleep
+    self.i2c.write8(self.__MODE1, newmode)        # go to sleep
+    self.i2c.write8(self.__PRESCALE, int(math.floor(prescale)))
+    self.i2c.write8(self.__MODE1, oldmode)
+    time.sleep(0.005)
+    self.i2c.write8(self.__MODE1, oldmode | 0x80)
+
+  def setPWM(self, channel, on, off):
+    "Sets a single PWM channel"
+    self.i2c.write8(self.__LED0_ON_L+4*channel, on & 0xFF)
+    self.i2c.write8(self.__LED0_ON_H+4*channel, on >> 8)
+    self.i2c.write8(self.__LED0_OFF_L+4*channel, off & 0xFF)
+    self.i2c.write8(self.__LED0_OFF_H+4*channel, off >> 8)
+
+
+
+

Adafruit_PWM_Servo_Driver/Servo_Example.py

@@ -0,0 +1,37 @@
+#!/usr/bin/python
+
+from Adafruit_PWM_Servo_Driver import PWM
+import time
+
+# ===========================================================================
+# Example Code
+# ===========================================================================
+
+# Initialise the PWM device using the default address
+# bmp = PWM(0x40, debug=True)
+pwm = PWM(0x40, debug=True)
+
+servoMin = 150  # Min pulse length out of 4096
+servoMax = 600  # Max pulse length out of 4096
+
+def setServoPulse(channel, pulse):
+  pulseLength = 1000000                   # 1,000,000 us per second
+  pulseLength /= 60                       # 60 Hz
+  print "%d us per period" % pulseLength
+  pulseLength /= 4096                     # 12 bits of resolution
+  print "%d us per bit" % pulseLength
+  pulse *= 1000
+  pulse /= pulseLength
+  pwm.setPWM(channel, 0, pulse)
+
+pwm.setPWMFreq(60)                        # Set frequency to 60 Hz
+while (True):
+  pwm.setPWM(15, 0, 150)                  # Slow ramp up servo speed
+  pwm.setPWM(11, 0, 150)
+  time.sleep(1)
+  pwm.setPWM(15, 0, 600)
+  pwm.setPWM(11, 0, 600)
+  time.sleep(1)
+
+
+