Motor Control

1. Introduction

In the steps of this tutorial

1. the your droid Micro Servo 9g (“servo motor”) is controlled
2. multiple PWM signals to control a dual motor h bridge and the servo motor are generated.

2. Prerequisites

• Arduino IDE has been installed
• Espressif board package has been added to the Arduino IDE
• ESP32C3 has been connected to the development computer (via USB cable)
• ESP32C3 has been selected as board on the development computer (in the Arduino IDE)
• The your droid Micro Servo 9g is available
• A compatible h bridge with motors is available
• Optional: an indicator to check the PWM frequency is available (e.g. LED, oszilloscope, …)

3. Basics

The servo motor and the h bridge are controlled by PWM signals.

The basic of PWM are described on Wikipedia: https://en.wikipedia.org/wiki/Pulse-width_modulation

The Espressif ESP32C3 has a dedicated hardware module, which can generate PWM signals. The Espressif ESP32C3 PWM hardware module is called LED Control (LEDC) and described in the Espressif documentation: https://docs.espressif.com/projects/esp-idf/en/stable/esp32c3/api-reference/peripherals/ledc.html

The library to control the ESP32C3’s LED Control module is described in the Espressif’s GitHub repository: https://github.com/espressif/arduino-esp32/blob/master/docs/en/api/ledc.rst

4. Implementation

4.1 Servo Motor Control

Example code: servo_ledc

• Example for Position ~0° with 50Hz and ~0.54ms duty cycle (=28 for 10b res.)
  • More detailed example for Position ~0° with 50Hz and 0.54ms duty cycle (=28 for 10b res.)
• Example for Position ~0 with 50Hz and ~2.50ms duty cycle (=128 for 10b res.))

4.2 Drive Motor Control

Example code: hbridge_ledc_withSliders

4.3 Multi PWM Signal Generation

Example code: servo_hbridge_ledc

• Comparison of servo motor control pin and a h bridge control pin
• Comparison of two h bridge control pins