Overview
Things
Story

Constitution
Move
Important Note

Published August 21, 2025

Robotic Arm Using M5Stack

I made a robotic arm using M5stack and Arduino. It uses SG90 servomotors to operate.

BeginnerFull instructions provided2 hours51

Things used in this project

Hardware components

M5Stack Core2 For AWS

M5Stack 8Servos Unit

https://docs.m5stack.com/en/unit/8Servos%20Unit

M5Stack UNIT 8Angle

M5Stack Unit PaHUB

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

SG90

Servomotor

Story

I created an Arduino program that uses M5stack Core2 to control Unit 8Servos with Unit 8Angle.

Unit 8Servos is connected to an SG90 servomotor, which moves the Robotic Arm.

Constitution

The Arduino program is written on the M5Stack Core2.

The Unit PaHUB is connected to PortA of the Core2.

The Unit 8Angle is connected to PaHUB Port1, and the Unit 8Servos is connected to PaHUB Port2.

Servomotors SG90 are connected to the Unit8 Servos.

You can move the SG90 by operating the 8Angle and controlling the 8Servo.

The Robotic arm's skeleton is made with a 3D printer.

The values for each channel are displayed in real time on the Core2 display.

In addition, the operating range can be limited to prevent the servomotor from becoming overloaded.

For details, refer to the program comments.

appearance

Move

Display

Important Note

The 8Angle library and 8Servos library provided by M5stack both defined constants with exactly the same names, _8bit and _12bit, internally.

This causes a name collision when compiling the program.

To avoid this, please change the function names individually.

Arduino/C++ Program

/*
 * : M5_Final_Realtime_Control_System
 * : 2025/08/18
 * :
 * - 8Angle8Servos2PaHub
 * :
 * - : Core2 -> PortA -> PaHub -> (ch0:8Angle, ch5:8Servos).
 * - 8Angle(CH1-8)8Servos(CH0-7)
 * - 
 * - LCD
 * - CardKB
 */

#include <M5Core2.h>
#include "M5_ANGLE8.h"      // 8Angle ()
#include "M5_UNIT_8SERVO.h" // 8Servos

// --- I2CPaHub ---
#define PAHUB_ADDR           0x70
#define ANGLE_HUB_CHANNEL    0
#define SERVOS_HUB_CHANNEL   5

// ---  ---
M5_ANGLE8      m5_8angle;
M5_UNIT_8SERVO m5_8servos;

// ---  ---
constexpr int NUM_SERVOS = 8; // 8

// ---  ---
// {, } 
const int servo_limits[NUM_SERVOS][2] = {
  {  5, 175 },  // Servo CH0 
  {  5, 175 },  // Servo CH1 
  {  5, 175 },  // Servo CH2 
  {  5, 175 },  // Servo CH3 
  {  5, 175 },  // Servo CH4 
  { 30, 150 },  // Servo CH5 
  {  5, 175 },  // Servo CH6 
  {  5, 175 }   // Servo CH7 
};

// ---  ---
uint8_t current_angles[NUM_SERVOS];

// --- : PaHub ---
void selectChannel(uint8_t channel) {
    Wire.beginTransmission(PAHUB_ADDR);
    Wire.write(1 << channel);
    Wire.endTransmission();
}

// ---  ---
void setup() {
    M5.begin();
    Wire.begin(32, 33);
    Serial.begin(115200);
    Serial.println("--- Realtime Control System (8 Servos with Individual Limits) ---");

    // ---  ---
    selectChannel(ANGLE_HUB_CHANNEL);
    if (!m5_8angle.begin()) {
        Serial.println("8Angle Error!"); M5.Lcd.fillScreen(RED); M5.Lcd.println("8Angle Error!"); while(1);
    }
    Serial.println("8Angle Initialized.");

    selectChannel(SERVOS_HUB_CHANNEL);
    if (!m5_8servos.begin(&Wire)) {
        Serial.println("8Servos Error!"); M5.Lcd.fillScreen(RED); M5.Lcd.println("8Servos Error!"); while(1);
    }
    m5_8servos.setAllPinMode(SERVO_CTL_MODE);
    Serial.println("8Servos Initialized.");

    // --- LCD ---
    M5.Lcd.fillScreen(BLACK);
    M5.Lcd.setTextColor(WHITE);
    M5.Lcd.setTextSize(2);
    M5.Lcd.setCursor(20, 10);
    M5.Lcd.println("8Angle -> 8Servos Realtime Control");
    for (int i = 0; i < NUM_SERVOS; i++) {
        int col = i / 4;
        int row = i % 4;
        M5.Lcd.setCursor(20 + col * 160, 60 + row * 40);
        M5.Lcd.printf("S%d:", i);
    }

    // ---  ---
    selectChannel(ANGLE_HUB_CHANNEL);
    for (int i = 0; i < NUM_SERVOS; i++) {
        uint16_t raw_val = m5_8angle.getAnalogInput(i, ANGLE8_12BIT);
        current_angles[i] = map(raw_val, 0, 4095, servo_limits[i][0], servo_limits[i][1]);
    }
    selectChannel(SERVOS_HUB_CHANNEL);
    for (int i = 0; i < NUM_SERVOS; i++) {
        m5_8servos.setServoAngle(i, current_angles[i]);
    }
}

// ---  ---
void loop() {
    // --- 1: 8Angle ---
    selectChannel(ANGLE_HUB_CHANNEL);
    for (int i = 0; i < NUM_SERVOS; i++) {
        uint16_t raw_val = m5_8angle.getAnalogInput(i, ANGLE8_12BIT);
        current_angles[i] = map(raw_val, 0, 4095, servo_limits[i][0], servo_limits[i][1]);
    }

    selectChannel(SERVOS_HUB_CHANNEL);
    for (int i = 0; i < NUM_SERVOS; i++) {
        m5_8servos.setServoAngle(i, current_angles[i]);
    }

    // --- 2: LCD ---
    for (int i = 0; i < NUM_SERVOS; i++) {
        int col = i / 4;
        int row = i % 4;
        int x_pos = 20 + col * 160 + M5.Lcd.textWidth("S0: ");
        int y_pos = 60 + row * 40;
        
        M5.Lcd.fillRect(x_pos, y_pos, M5.Lcd.textWidth(" 000"), M5.Lcd.fontHeight(), BLACK);
        M5.Lcd.setCursor(x_pos, y_pos);
        M5.Lcd.printf("%3d", current_angles[i]);
    }

    delay(20);
}

Credits

XAP

1 project • 0 followers

Robotic Arm Using M5Stack