pca9865.py now a library.

lib/pca9865.py

@@ -1,14 +1,17 @@
 # MicroPython PCA9865 16 servo controller driver.
+#NOTE: I tried writing 16 bit values for PWM but it crashed the controller requiring a power cycle to reset.
 
 import pyb
 from time import sleep_us
 
 class pca9865(object):
+  """16 servo contoller. Use index 0-15 for the servo #."""
 
   _ADDRESS = 0x40
   _MODE1 = const(0)
   _PRESCALE = const(0xFE)
-  _LED0_ON_L = const(0x6)
+
+  _LED0_ON_L = const(0x6)                       #We only use LED0 and offset 0-16 from it.
 #  _LED0_ON_H = const(0x7)
 #  _LED0_OFF_L = const(0x8)
 #  _LED0_OFF_H = const(0x9)
@@ -24,7 +27,7 @@ class pca9865(object):
   _PULSERANGE = const(450)
 
   def __init__(self, aLoc) :
-    """aLoc I2C pin location is either 1 for 'X' or 2 for 'Y'."""
+    """aLoc I2C pin location is either 1, 'X', 2 or'Y'."""
     super(pca9865, self).__init__()
     self.i2c = pyb.I2C(aLoc, pyb.I2C.MASTER)
 #    print(self.i2c)
@@ -33,16 +36,20 @@ class pca9865(object):
     self.reset()
 
   def read( self, aLoc ) :
+    """Read 8 byte value and return in bytearray"""
     return self.i2c.mem_read(1, self._ADDRESS, aLoc)
 
   def write( self, aVal, aLoc ) :
+    """Write 8 bit value to given address.  aVal may be an int buffer."""
     self.i2c.mem_write(aVal, self._ADDRESS, aLoc)
 
   def reset( self ):
+    """Reset the controller and set default frequency."""
     self.write(0, _MODE1)
     self.setfreq(_DEFAULTFREQ)
 
   def setfreq( self, aFreq ) :
+    """Set frequency for all servos.  A good value is 60hz (default)."""
     aFreq *= 0.9  #Correct for overshoot in frequency setting.
     prescalefloat = (6103.51562 / aFreq) - 1  #25000000 / 4096 / freq.
     prescale = int(prescalefloat + 0.5)
@@ -56,33 +63,28 @@ class pca9865(object):
     sleep_us(50)
     self.write(oldmode | 0xA1, _MODE1)  #This sets the MODE1 register to turn on auto increment.
 
-  def setPWM( self, aServo, aOn, aOff ) :
+  def setpwm( self, aServo, aOn, aOff ) :
     """aServo = 0-15.
        aOn = 16 bit on value.
        aOff = 16 bit off value.
     """
-    #Data is on low, on high, off low and off high.  That's 4 bytes each servo.
-
-    loc = _LED0_ON_L + (aServo * 4)
+    if 0 <= aServo <= 15 :
+      #Data = on-low, on-high, off-low and off-high.  That's 4 bytes each servo.
+      loc = _LED0_ON_L + (aServo * 4)
 #    print(loc)
-    self._buffer[0] = aOn
-    self._buffer[1] = aOn >> 8
-    self._buffer[2] = aOff
-    self._buffer[3] = aOff >> 8
-    self.write(self._buffer, loc)
+      self._buffer[0] = aOn
+      self._buffer[1] = aOn >> 8
+      self._buffer[2] = aOff
+      self._buffer[3] = aOff >> 8
+      self.write(self._buffer, loc)
+    else:
+      raise Exception('Servo index {} out of range.'.format(str(aServo)))
 
-  def setpin( self, aServo, aVal ) :
-    on = 0
-    off = min(aVal, 4095)
-    if off == 4095 :
-      on = 4096
-      off = 0
-    elif aVal == 0 :
-      off = 4096
-
-    self.setPWM(aServo, on, off)
+  def off( self, aServo ) :
+    """Turn off a servo."""
+    self.setpwm(aServo, 0, 0)
 
   def setangle( self, aServo, aAng ) :
     """Set the angle 0-100%"""
     val = _MINPULSE + ((_PULSERANGE * aAng) // 100)
-    self.setPWM(aServo, 0, val)
+    self.setpwm(aServo, 0, val)