Multiple-Servo-Driver

An ArduinoProgram to drive up to 6 servos on an Arduino Nano

This program allows control of up to six low cost servo motors which may be used for controlling model railway turnouts, signals or accessories using a small arduino processor. It was originnaly intended for an arduino Nano. It would be possible to use this on an arduino Uno.

The program allows setting end points for the movement of the servos using a number of pushbuttons. These values are stored in the EEPROM of the microprocessor.

The servos are operated by switches attached to the relevant input pins. The programming is carried out by buttons attached to the programming pins.

Please Note: The servo control pins are attached to the Nano pins, but the servos should be powered by an indepedent 5V power supply. Attempting to drive the servos from the Nano 5V pin would undoubtedly destroy the Nano.

Pin Configurations

Servo Pins

• Servo 1 to pin 8
• Servo 2 to pin 9
• Servo 3 to pin 10
• Servo 4 to pin 11
• Servo 5 to pin 12
• servo 6 to pin 3

Lever Pins The operating levers/switches connect to the following pins:

• Lever 1 to pin 14/A0
• Lever 2 to pin 15/A1
• Lever 3 to pin 16/A2
• Lever 4 to pin 17/A3
• Lever 5 to pin 18/A4
• Lever 6 to pin 19/A5

Programming Buttons Four buttons can be connected temporarily to the following four pins in order to set the servo end points:

• Low Button - Pin 7
• Prog Button - Pin 6
• High Button - Pin 5
• Mode Button - Pin 4

Programming Method

1. To put the unit into program mode press the PROG button. This will set the Nano into program mode on Servo Channel 1. The Nano will flash the internal LED once to indicate channel. The servo will be centralised.
2. To move the servo arm to the low position press the LOW button. If you hold the button down the arm will keep moving.
3. To move the servo arm to the high position press the HIGH button.
4. If you wish to reverse the Low and High postions press gthe Mode button once.
5. Once you are happy with the settings press the Mode button again. This will move up to the next Servo channel and the onboard LED will start flashing at a different rate (i.e. 2 flashes for channel 2 and so on).
6. Once you have reached the last channel the servos will move to the low positions, the LED will stop flashing and the setting will be saved to EEPROM
7. Operating a Lever/Switch should now operate the servo.

Source Files

This repository contains three source files.

• ServoDriverMultiv4.ino. This is the main source file for the code which will control six servos.#
• ServoDriverMultiTwoServos.ino. This file has been configured to operate two servos.
• ServoDriverMultiFourServos.ino. This file has been configured to operate four servos.

The code uses three libraries which will need to be loaded into the Arduino IDE

1. EEPROM - This is part of the Arduino infrasructure.
2. Button - This is a small library written by Michael Adams (Copyright (C) 2016 Michael D K Adams.) which can be downloaded from github. https://github.com/madleech/Button. the version used is included here for completeness. Downoad the entire folder to your "Libaries" folder.
3. VarSpeedServo - This library is a variation of the Arduino servo.h libraryand is available at https://github.com/netlabtoolkit/VarSpeedServo. Once again the version I have used is included here.

This code was written on the Arduino IDE. to use under PlatformIO on VSCODE rename the .ino file to .cpp and move the Startup and Loop functions to the end of the code.