PCA9685 driver does not support all modes (MODE2)

[Michel Lawaty]

The PCY9685 PWM chip supports different output modes.

Therefore it has a register MODE2 - Mode register 2 (address 01h) bit description

, which has following bit settings:

• INVRT[1] R/W 0* Output logic state not inverted. Value to use when external driver used.
  
• OCH R/W 0* Outputs change on STOP command[2].
  
• OUTDRV[1] R/W 0 The 16 LEDn outputs are configured with an open-drain structure.
  
• 0 OUTNE[1:0][4] R/W 00* When OE = 1 (output drivers not enabled), LEDn = 0.
  

These are important for changing the output driver.

Unfortunately the driver in webiopi does not support this. 

And my setup with connected Test-LED does not work with the actual driver.

So I tried to add following to the code, but it didn't work out. Also, I don't understand why "M1_SLEEP" is set to '1' ?? Then the chips sleeps, or not?

class PCA9685(PWM, I2C):

    MODE1   = 0x00

    MODE2   = 0x01

    PWM_BASE = 0x06

    PRESCALE = 0xFE

    M1_SLEEP    = 1<<4

    M1_AI       = 1<<5

    M1_RESTART  = 1<<7

    M2_OUTDRV   = 1<<2

    M2_OUTNE_1  = 1<<1

    M2_OUTNE_0  = 1<<0

    def __init__(self, slave=0x40, frequency=50):

        I2C.__init__(self, toint(slave))

        PWM.__init__(self, 16, 12, toint(frequency))

        self.VREF = 0

        self.prescale = int(25000000.0/((2**12)*self.frequency))

        self.mode2 = self.M2_OUTDRV | self.M2_OUTNE_0

        self.writeRegister(self.MODE2, self.mode2)

        self.mode1 = self.M1_RESTART | self.M1_AI

        self.writeRegister(self.MODE1, self.M1_SLEEP)

        self.writeRegister(self.PRESCALE, self.prescale)

        time.sleep(0.01)

        self.writeRegister(self.MODE1, self.mode1)