pca9685.py

#!/usr/bin/python
#
# PCA9685 Library
# Purely used for Pi2Go, so not as flexible as other libraries
#
# Created by Gareth Davies, Feb 2016
# Copyright 4tronix
#
# This code is in the public domain and may be freely copied and used
# No warranty is provided or implied
#
#======================================================================

from __future__ import print_function
import smbus, time
bus = smbus.SMBus(1)

PCA = 0x40    # Fixed I2C Address of PC9685
SERVOS = 6
RED = 14
GREEN = 10
BLUE = 6
VALIDIO = False

def init():
    global VALIDIO
    try:
        bus.write_byte_data(PCA, 1, 0x04)  # set Mode2 outputs to push-pull
        mode1 = bus.read_byte_data(PCA, 0) # get current Mode1 register
        mode1 &= 0x7f # ignore the reset bit
        mode1 |= 0x10 # set Sleep bit
        bus.write_byte_data(PCA, 0, mode1) # sleep
        bus.write_byte_data(PCA, 254, 101)    # set prescaler
        mode1 &= 0xef # clear Sleep bit
        bus.write_byte_data(PCA, 0, mode1 | 0x80) # wake up
        time.sleep(0.005)
        VALIDIO = True
    except:
        print ("No I2C Detected")

def setServo(servo, degrees):
    # note servo 0 is output 12 (ie. offset 48) on the PCA9685
    # change degrees to a value between 175 (-90) to 575 (+90)
    if VALIDIO:
        if (servo>=0) and (servo<=16) and (degrees>= -90) and (degrees<=90):
            start = 0
            stop = int(175 + ((degrees + 90) * 400) / 180)
            bus.write_byte_data(PCA, SERVOS + servo*4 + 0, start & 0xff)
            bus.write_byte_data(PCA, SERVOS + servo*4 + 1, start >> 8)
            bus.write_byte_data(PCA, SERVOS + servo*4 + 2, stop & 0xff)
            bus.write_byte_data(PCA, SERVOS + servo*4 + 3, stop >> 8)

def stopServo(servo):
    if VALIDIO:
        if (servo>=0) and (servo<=16):
            bus.write_byte_data(PCA, SERVOS + servo*4 + 0, 0)
            bus.write_byte_data(PCA, SERVOS + servo*4 + 1, 0)
            bus.write_byte_data(PCA, SERVOS + servo*4 + 2, 0)
            bus.write_byte_data(PCA, SERVOS + servo*4 + 3, 0)

def setRGBLED(led, red, green, blue):
    if VALIDIO:
        bus.write_byte_data(PCA, RED + led*12 + 0, 0)
        bus.write_byte_data(PCA, RED + led*12 + 1, 0)
        bus.write_byte_data(PCA, RED + led*12 + 2, red & 0xff)
        bus.write_byte_data(PCA, RED + led*12 + 3, red >> 8)
        bus.write_byte_data(PCA, GREEN + led*12 + 0, 0)
        bus.write_byte_data(PCA, GREEN + led*12 + 1, 0)
        bus.write_byte_data(PCA, GREEN + led*12 + 2, green & 0xff)
        bus.write_byte_data(PCA, GREEN + led*12 + 3, green >> 8)
        bus.write_byte_data(PCA, BLUE + led*12 + 0, 0)
        bus.write_byte_data(PCA, BLUE + led*12 + 1, 0)
        bus.write_byte_data(PCA, BLUE + led*12 + 2, blue & 0xff)
        bus.write_byte_data(PCA, BLUE + led*12 + 3, blue >> 8)