The Dynamixel Hat is a board capable of communicating the raspberry Pi ( Serial ) with the Dynamixel servos by using the 74LS241 Tri-state Buffer connected to 3-pin Molex connectors.

The board contains a TI TPS62143 regulator that steps down the voltage to power up the Raspberry Pi Zero that can be power on or off with the onboard slide switch. The TPS62143 is a synchronous step-down DC-DC converter optimized for applications with high power density.

This board accepts 2S and 3S Lipo batteries, the DC-DC converter accepts up to 17 Volts but the motors recommended voltage is 11.1V ( 3S Lipo ) as the MAX Input voltage is around 16 Volts.

The boards incorporate two I2C ports for sensors for your robotic project. These are JST 1 mm pitch and 4-pin connectors compatible with many boards on the QWIIC family.

There are also 3 LEDs and 3 Buttons for notification and interaction with the electronics, the buttons are programable through the Raspberry GPIOs and 1 LED also GPIO Configurable, the other 2 LEDs are the Activity and PowerOn notification.

Test Code:

import RPi.GPIO as GPIO import serial import time GPIO.setwarnings(False) GPIO.setmode(GPIO.BCM) GPIO.setup(18,GPIO.OUT) # Control Data Direction Pin GPIO.setup(6,GPIO.OUT) # Blue LED Pin GPIO.setup(26,GPIO.IN) # S2 Push Button Pin GPIO.setup(19,GPIO.IN) # S3 Push Button Pin GPIO.setup(13,GPIO.IN) # S4 Push Button Pin Dynamixel=serial.Serial("/dev/ttyS0",baudrate=1000000,timeout=0.1, bytesize=8) # UART in ttyS0 @ 1Mbps while True: if GPIO.input(26): GPIO.output(6,GPIO.LOW) else: GPIO.output(6,GPIO.HIGH) GPIO.output(18,GPIO.HIGH) Dynamixel.write(bytearray.fromhex("FF FF 01 05 03 1E CD 00 0B")) # Move Servo with ID = 1 to position 205 GPIO.output(18,GPIO.LOW) startDynamixel = Dynamixel.read() startDynamixel = Dynamixel.read() idDynamixel = Dynamixel.read() lenghtDynamixel = Dynamixel.read() errorDynamixel = Dynamixel.read() chkDynamixel = Dynamixel.read() print("Servo ID = " , int.from_bytes(idDynamixel,byteorder='big') , " Errors = ", int.from_bytes(errorDynamixel,byteorder='big')) time.sleep(1) if GPIO.input(19): GPIO.output(6,GPIO.LOW) else: GPIO.output(6,GPIO.HIGH) GPIO.output(18,GPIO.HIGH) Dynamixel.write(bytearray.fromhex("FF FF 01 04 02 2A 01 CD")) # Read Voltage of Servo with ID = 1 GPIO.output(18,GPIO.LOW) startDynamixel = Dynamixel.read() startDynamixel = Dynamixel.read() idDynamixel = Dynamixel.read() lenghtDynamixel = Dynamixel.read() errorDynamixel = Dynamixel.read() voltDynamixel = Dynamixel.read() chkDynamixel = Dynamixel.read() print("Servo Voltage = " , int.from_bytes(voltDynamixel,byteorder='big')) GPIO.output(18,GPIO.HIGH) Dynamixel.write(bytearray.fromhex("FF FF 01 04 02 2B 01 CC")) # Read Temperature of Servo with ID = 1 GPIO.output(18,GPIO.LOW) startDynamixel = Dynamixel.read() startDynamixel = Dynamixel.read() idDynamixel = Dynamixel.read() lenghtDynamixel = Dynamixel.read() errorDynamixel = Dynamixel.read() tempDynamixel = Dynamixel.read() chkDynamixel = Dynamixel.read() print("Servo Temperature = " , int.from_bytes(tempDynamixel,byteorder='big')) GPIO.output(18,GPIO.HIGH) Dynamixel.write(bytearray.fromhex("FF FF 01 04 02 24 02 D2")) # Read Position of Servo with ID = 1 GPIO.output(18,GPIO.LOW) startDynamixel = Dynamixel.read() startDynamixel = Dynamixel.read() idDynamixel = Dynamixel.read() lenghtDynamixel = Dynamixel.read() errorDynamixel = Dynamixel.read() posDynamixel = Dynamixel.read(2) chkDynamixel = Dynamixel.read() print("Servo Position = " , int.from_bytes(posDynamixel,byteorder='little')) time.sleep(1) if GPIO.input(13): GPIO.output(6,GPIO.LOW) else: GPIO.output(6,GPIO.HIGH) GPIO.output(18,GPIO.HIGH) Dynamixel.write(bytearray.fromhex("FF FF 01 05 03 1E 32 03 A3")) # Move Servo with ID = 1 to position 816 GPIO.output(18,GPIO.LOW) startDynamixel = Dynamixel.read() startDynamixel = Dynamixel.read() idDynamixel = Dynamixel.read() lenghtDynamixel = Dynamixel.read() errorDynamixel = Dynamixel.read() chkDynamixel = Dynamixel.read() print("Servo ID = " , int.from_bytes(idDynamixel,byteorder='big') , " Errors = ", int.from_bytes(errorDynamixel,byteorder='big')) time.sleep(1)

Make sure to add the following to your Raspberry config file at /boot/config.txt:

enable_uart=1 init_uart_clock=16000000

Assembly video: