4-DOF Robotic Arm Controller

// 4-DOF Robotic Arm Controller with PCA9685
// MakersDeck Arduino Project

#include <Wire.h>
#include <Adafruit_PWMServoDriver.h>

// Create the PWM driver object
Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver();

// PCA9685 Channel definitions
#define BASE_CH 0
#define SHOULDER_CH 1
#define ELBOW_CH 2
#define GRIPPER_CH 3

// Servo Pulse definitions (typical for MG996R/SG90)
#define SERVOMIN  150 // Minimum pulse length count
#define SERVOMAX  600 // Maximum pulse length count
#define SERVO_FREQ 50 // Analog servos run at ~50 Hz

// Potentiometer Pin definitions
#define POT_BASE A0
#define POT_SHOULDER A1
#define POT_ELBOW A2
#define POT_GRIPPER A3

#define BTN_RECORD 7
#define BTN_PLAY 8

// Recording storage
#define MAX_STEPS 100
int recording[MAX_STEPS][4];
int stepCount = 0;

void setup() {
    Serial.begin(9600);
    
    pwm.begin();
    pwm.setOscillatorFrequency(27000000);
    pwm.setPWMFreq(SERVO_FREQ);
    
    pinMode(BTN_RECORD, INPUT_PULLUP);
    pinMode(BTN_PLAY, INPUT_PULLUP);
    
    // Center all servos
    setServoAngle(BASE_CH, 90);
    setServoAngle(SHOULDER_CH, 90);
    setServoAngle(ELBOW_CH, 90);
    setServoAngle(GRIPPER_CH, 90);
    
    Serial.println("Robotic Arm Ready (PCA9685)!");
}

void loop() {
    // Read potentiometers
    int baseAngle = map(analogRead(POT_BASE), 0, 1023, 0, 180);
    int shoulderAngle = map(analogRead(POT_SHOULDER), 0, 1023, 0, 180);
    int elbowAngle = map(analogRead(POT_ELBOW), 0, 1023, 0, 180);
    int gripperAngle = map(analogRead(POT_GRIPPER), 0, 1023, 0, 90);
    
    // Move servos via PCA9685
    setServoAngle(BASE_CH, baseAngle);
    setServoAngle(SHOULDER_CH, shoulderAngle);
    setServoAngle(ELBOW_CH, elbowAngle);
    setServoAngle(GRIPPER_CH, gripperAngle);
    
    // Check record button
    if (digitalRead(BTN_RECORD) == LOW) {
        if (stepCount < MAX_STEPS) {
            recording[stepCount][0] = baseAngle;
            recording[stepCount][1] = shoulderAngle;
            recording[stepCount][2] = elbowAngle;
            recording[stepCount][3] = gripperAngle;
            stepCount++;
            Serial.print("Recorded step: ");
            Serial.println(stepCount);
        }
        delay(200);
    }
    
    // Check play button
    if (digitalRead(BTN_PLAY) == LOW && stepCount > 0) {
        Serial.println("Playing sequence...");
        playSequence();
    }
    delay(20);
}

void setServoAngle(uint8_t n, double angle) {
    double pulselen = map(angle, 0, 180, SERVOMIN, SERVOMAX);
    pwm.setPWM(n, 0, pulselen);
}

void playSequence() {
    for (int i = 0; i < stepCount; i++) {
        setServoAngle(BASE_CH, recording[i][0]);
        setServoAngle(SHOULDER_CH, recording[i][1]);
        setServoAngle(ELBOW_CH, recording[i][2]);
        setServoAngle(GRIPPER_CH, recording[i][3]);
        delay(100);
    }
    Serial.println("Sequence complete!");
}