nservo - PCA9685 - Raspberry Pi I2C servo driver

A driver for the popular PCA9685 servo driver breakout boards.

Usage Example

from nservo import PCA9685
import time

# Initialize the PCA9685 driver
pwm = PCA9685(address=0x40, i2c_device_number=1)

# Use the control context manager to set a servo position
with pwm.control() as set_servo:
    for i in range(3):
        set_servo(servo_number=0, position=0.0)
        time.sleep(0.5)
        set_servo(servo_number=0, position=0.3)
        time.sleep(0.5)
        set_servo(servo_number=0, position=0.8)
        time.sleep(0.5)

Setup Instructions

Wire up SDA to pin 2 and SDC to pin 3 of the raspberry pi 40 pin GPIO.

On the pi terminal;

sudo raspi-config
# Open > Interface > Enable i2c

sudo apt-get install i2c-tools
sudo i2cdetect -y 1

For my breakout board this finds addresses at 0x40 and 0x70

0x70 is the All Call address (I think we don't care about this unless using a string of multiple PCA9685 devices)
0x40 is the configurable device address
- This is the address that we care about
- I think you can adjust jumpers on your breakout board to adjust this address

This library requires smbus. This may get installed automatically if you install this library using pip? My setup Pi OS version makes me use apt-get. To manually install smbus dependency for this library:

sudo apt install python3-smbus

VS Code Remote ssh tips

You will need the following to use this library if you use VS Code Jypyter notebooks via SSH like I did:

sudo apt-get install python3-ipykernel

Other Notes;

PWM control signal is 50hz with pulse between 1ms and 2ms or on time of 5% to 10% duty

Audio

I got headless raspberry pi 5 audio working fastest using mpg123 over bluetooth.

use this guide https://gist.github.com/actuino/9548329d1bba6663a63886067af5e4cb.