Waveshare Servo Driver HAT: 16-Channel PWM Control

The Waveshare Servo Driver HAT uses PCA9685 to control up to 16 servos from just two I2C pins.

Specs

• PCA9685 16-channel, 12-bit PWM
• I2C address 0x40 (configurable)
• Separate servo power input (5-6V)
• Stackable — chain multiple HATs for 32+ servos

Setup

Mount HAT, enable I2C, connect external 5V power for servos.

pip3 install adafruit-circuitpython-pca9685 adafruit-circuitpython-motor

Python Code

from adafruit_pca9685 import PCA9685
from adafruit_motor import servo
import busio, board
i2c = busio.I2C(board.SCL, board.SDA)
pca = PCA9685(i2c); pca.frequency = 50
s = servo.Servo(pca.channels[0])
s.angle = 0; import time; time.sleep(1)
s.angle = 90; time.sleep(1); s.angle = 180

Projects

• Robotic arm (6-axis requires 6 channels)
• Animatronic figure with multiple moving parts
• Pan-tilt camera mount
• Hexapod robot (18 servos across 2 HATs)
• Automated blinds/curtain opener

Tips

• Always use external power for servos — Pi cannot supply enough current.
• Add decoupling capacitors (1000uF) across servo power to prevent brownouts.
• Start servos at centre position to avoid sudden jerks at power-on.

Frequently Asked Questions

Max servos?

16 per HAT. Stack up to 62 HATs on I2C for 992 servos.

Can I control DC motors?

Yes, but better to use a motor driver. PCA9685 outputs PWM only (no H-bridge).

Servo jitter?

PCA9685 has hardware PWM, so jitter is minimal. External power supply noise can cause jitter — use capacitors.

Works with Pi 5?

Yes, standard I2C interface is compatible.

Conclusion

The Servo Driver HAT is essential for multi-servo robotics projects, freeing GPIO pins and providing clean PWM signals.

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