Servos

Easily control your robotic movements using the Echo's dedicated servo ports.

Intro

Servos are motors that can move to precise positions and hold them steady. They're perfect for moving robot arms, steering mechanisms, camera gimbals, and any project where you need accurate positioning.

Overview

The Echo board provides 10 dedicated servo ports (labeled 0-9), allowing you to control up to 10 servos at once.

⚠️ Important Power Limitation: The combined current draw of all your servos must not exceed 10 Amperes. This is plenty for most hobby projects, but be mindful when using multiple heavy-duty servos.

Function	Purpose
init()	Initialize driver (required!)
init(freq)	Initialize with custom frequency
setServoAngle(port, angle)	Move specific servo to a specific angle
setAllZero()	Reset all servos to 0°

Getting Started

Basic Setup

Every servo project starts with these essential steps:

#include <EchoLib.h>

ServoDriver servoDriver;

void setup() {
    servoDriver.init(); // CRITICAL: Always call this first!
}

void loop() {
    // Your servo control code here
}

🚨 Critical Note: You must call servoDriver.init() in your setup() function. Skipping this step will cause crashes!

Your First Moving Servo

Let's make a servo move to 90 degrees (middle position):

#include <EchoLib.h>

ServoDriver servoDriver;

void setup() {
    servoDriver.init();
    
    // Move servo on port 0 to 90 degrees
    servoDriver.setServoAngle(0, 90);
}

void loop() {
    // Servo holds position automatically
}

The servo will move to 90 degrees and stay there. No code needed in loop() to hold the position!

API Reference

Initialization

void init()

Initializes the servo driver with default settings (60 Hz frequency). Always call this first!

void setup() {
    servoDriver.init(); // Required - prevents crashes
}

init(frequency)

void init(int freq)

Initializes the servo driver with a custom frequency. Most servos work best at 50-60 Hz.

void setup() {
    servoDriver.init(50); // 50 Hz for standard servos
}

Servo Control

setServoAngle()

void setServoAngle(int servo, int angle)

Moves a specific servo to the desired angle.

Parameters:

• servo: Servo port number (0-9, matches the labels on your Echo board)

• angle: Target angle in degrees (0-180)

Examples:

// Move servo on port 0 to 0 degrees (far left)
servoDriver.setServoAngle(0, 0);

// Move servo on port 3 to 90 degrees (center)
servoDriver.setServoAngle(3, 90);

// Move servo on port 7 to 180 degrees (far right)
servoDriver.setServoAngle(7, 180);

setAllZero()

void setAllZero()

Instantly moves all connected servos to their 0-degree position. Great for resetting your robot to a "home" position.

// Reset all servos to starting position
servoDriver.setAllZero();

Practical Examples

Sweeping Servo

Make a servo sweep back and forth continuously:

#include <EchoLib.h>

ServoDriver servoDriver;

void setup() {
    servoDriver.init();
}

void loop() {
    // Sweep from 0 to 180 degrees
    for (int angle = 0; angle <= 180; angle++) {
        servoDriver.setServoAngle(0, angle);
        delay(20); // Small delay for smooth movement
    }
    
    // Sweep back from 180 to 0 degrees
    for (int angle = 180; angle >= 0; angle--) {
        servoDriver.setServoAngle(0, angle);
        delay(20);
    }
}

Multi-Servo Robot Arm

Control multiple servos to create a simple robot arm:

#include <EchoLib.h>

ServoDriver servoDriver;

void setup() {
    servoDriver.init();
    
    // Start in "home" position
    servoDriver.setAllZero();
    delay(1000);
    
    Serial.begin(115200);
    Serial.println("Robot arm ready!");
}

void loop() {
    // Move to "grab" position
    servoDriver.setServoAngle(0, 45);  // Base rotation
    servoDriver.setServoAngle(1, 90);  // Shoulder
    servoDriver.setServoAngle(2, 135); // Elbow
    delay(2000);
    
    // Move to "lift" position
    servoDriver.setServoAngle(1, 45);  // Lift shoulder
    servoDriver.setServoAngle(2, 90);  // Straighten elbow
    delay(2000);
    
    // Return home
    servoDriver.setAllZero();
    delay(2000);
}

Interactive Servo Control

Control servos through the Serial Monitor:

#include <EchoLib.h>

ServoDriver servoDriver;

void setup() {
    Serial.begin(115200);
    servoDriver.init();
    
    Serial.println("Servo Controller Ready!");
    Serial.println("Commands:");
    Serial.println("- Type 'servo port angle' (e.g., 'servo 0 90')");
    Serial.println("- Type 'home' to reset all servos");
}

void loop() {
    if (Serial.available()) {
        String command = Serial.readStringUntil('\n');
        command.trim();
        
        if (command == "home") {
            servoDriver.setAllZero();
            Serial.println("All servos moved to home position");
        }
        else if (command.startsWith("servo ")) {
            // Parse "servo port angle"
            int firstSpace = command.indexOf(' ', 6);
            if (firstSpace > 0) {
                int port = command.substring(6, firstSpace).toInt();
                int angle = command.substring(firstSpace + 1).toInt();
                
                if (port >= 0 && port <= 9 && angle >= 0 && angle <= 180) {
                    servoDriver.setServoAngle(port, angle);
                    Serial.println("Servo " + String(port) + " moved to " + String(angle) + " degrees");
                } else {
                    Serial.println("Invalid values. Port: 0-9, Angle: 0-180");
                }
            }
        }
    }
}

Troubleshooting

Common Issues

Servo doesn't move:

• ✅ Did you call servoDriver.init() in setup()?

• ✅ Is the servo properly connected to the correct port?

• ✅ Is your power supply adequate for your servos?

Servo jitters or moves erratically:

• Try different frequency: servoDriver.init(50) instead of default

• Add small delays between servo commands

• Check for loose connections

Multiple servos don't work:

• Verify total current draw is under 10A

• Test servos individually first

• Ensure adequate power supply

Code crashes:

• Most crashes happen when init() is not called

• Always initialize before controlling servos

Tips for Success

1. Always initialize first: Call servoDriver.init() before any servo commands

2. Start simple: Test one servo before adding multiple servos

3. Use delays: Add small delays between movements for smooth motion

4. Check connections: Ensure servos are firmly connected to the correct ports

5. Monitor power: Keep total current under 10A limit

6. Test angles: Servo range is 0-180 degrees - values outside this range are automatically clamped