RL78 G23 128p FPB ServoMotor (Arduino™ Sketch)

Introduction

• This page describes how to make a servo motor perform reciprocating motion from 0 to 180 degrees
• For basic information such as how to install the Arduino IDE, Arduino libraries, and how to write sketches to the board, please refer to the Quick Start Guide

Operating Environment and Products Used

This page uses the following environment and products

Hardware

• RL78/G23-128p Fast Prototyping Board
• Micro Servo SG-90

Software

• Arduino IDE 2.3.6
• RL78/G23-128p FPB Arduino Library v1.2.0

Pin Connections

• Connect the SG-90 and RL78/G23-128p FPB as shown below

SG-90 Pin	RL78/G23-128p FPB Pin
SIG (Orange)	9
+V (Red)	5V
GND (Brown)	GND

Selecting the Sample Sketch

• Open the Arduino IDE and select “File” → “Examples” → “Servo” → “Sweep”

Compile, Upload, and Operation Check

• Compile and Upload the sketch

  • Select “Upload” in the Arduino IDE to start compiling and writing

• If the servo motor moves back and forth from 0 to 180 degrees as shown below, it is working correctly
  

Example Modifications to the Sample Sketch

Change the Servo Motor Target Angle

• You can set the angle using myservo.write(angle_in_degrees);

• Modify the sketch as shown below to set the target angle to 20 degrees

  Lines 24–33
  -  for(pos = 0; pos <= 180; pos += 1) // goes from 0 degrees to 180 degrees 
  -    {                                  // in steps of 1 degree 
  -      myservo.write(pos);              // tell servo to go to position in variable 'pos' 
  -      delay(15);                       // waits 15ms for the servo to reach the position 
  -    } 
  -    for(pos = 180; pos>=0; pos-=1)     // goes from 180 degrees to 0 degrees 
  -    {                                 
  -      myservo.write(pos);              // tell servo to go to position in variable 'pos' 
  -      delay(15);                       // waits 15ms for the servo to reach the position 
  -    } 
  +  myservo.write(20);

  • Actual operation
    

Change SG-90 SIG Pin to Pin 2

• To change the pin number, modify the number in myservo.attach(9); on line 19 to the desired pin number

• The following pins can be used for connecting the SIG pin Pin list here:

  Pins Compatible with Servo Motor
  0–19, 23, 25–29, 31–56, 58, 59, 62–71, 74–89, 92–118

• Example: Change SIG pin from pin 9 to pin 2

  • Change the pin connections as follows

    SG-90 Pin	RL78/G23-128p FPB Pin
    SIG (Orange)	2
    +V (Red)	5V
    GND (Brown)	GND

• Modify the sketch as shown below to set the SIG pin to pin 2

  Line 19
  -  myservo.attach(9);
  +  myservo.attach(2);