Last Updated: 08/01/2024
#58 PCA9685 Level Crossing Barriers, Lights and Sound
Projects >> #58 PCA9685 Level Crossing Barriers, Lights and Sound
PCA9685 Level Crossing Servo Barriers, LED Lights, DY-SV5W MP3 Sound
This project adds sound to the previous Level Crossing project Arduino and PCA9685 Model Railway Level Crossing Servo Barriers and LED Lights so only the modifiications will be discussed in the video.
In this version the movement will be triggered by a button that could be replaced by a block detector or sensor.
I have also added a DY-SV5W MP3 player to add the barrier alarm sounds.
I used this crossing in Pirton just south of Worcester to get the light and barrier timings as well as recording the sound.
Pinout and wiring diagrams
The LED's and servos work exactly the same way as the previous tutorial
However there is now a single button on pin 9 added with a PULL DOWN resistor for triggering the barrier close and raise.
I have also added the DY-SV5W MP3 player using Software Serial to pins 10 and 11
as before you will need a seperate 5v DC power supply to power the PCA9685 boards as the Arduino/USB power supply will not be able to provide enough power... you have been warned!
Pins
A5 to PCA9685 SCL
A4 to PCA9685 SDA
Make sure you have 5v going to the PCA9685 board as well as the VCC and GND. One powers the circuitry, the other supply powers the servo.
Wiring:for a few common boards
SDA/SCL connections
Arduino UNO:
A4 (SDA), A5 (SCL)
:
Arduino Mega 2560:
20 (SDA), 21 (SCL)
:
ESP32: 21(SDA), 22 (SCL)
For other Arduino boards see:https://www.arduino.cc/en/reference/wire
The Sound file
The sound file wasn't perfect as this isn't a project that I will be going on my layout, however the method was as follows.
1: I went to the crossing and recorded the barrier using the sound recorder on my Phone.
2: I imported the sound into Audacity (free at https://www.audacityteam.org/).
3: I edited the sound file to get the best bit of the barrier sound.
4: I copied and pasted the file to increase it's length. Car needs to be taken at the join of the samples.
5: I repeated the process until I have a file 3 minutes long... longer than the expected time for any train to pass.
6: The MP3 file was exported to the SD card in the DY-SV5W MP3 player
Connection Test 1 ...IMPORTANT
Bad wiring is one of the biggest problems with Arduino projects so run this test to make sure your board is being found before doing anythine else.
Once you have connected your board up as shown above check that it can be found.
If you are using an Arduino board go to File>Examples>
Wire>I2c_scanner and upload the skecth to your board.
if all goes well your serial Monitor will display something like
Scanning...
I2C device found at address 0x40 !
done
Once your device has been found it's time to add the LED's
Connection Test 2 ...Board and Servo Test
First make sure you have the Adafruit PWM Servo Library installed.
Tools>Manage Libraries>
Type Adafruit PWM Servo Library in the serach bar.
If it is not installed install it.
Connect the board according to the circuit diagram.
Now download a test file from the Adafruit PWM servo Library examples.
File>Examples>Adafruit PWM servo Driver Library>servo.
Load the sketch and in the Serial Monitor you should see something like:
8 channel Servo test!
0
1
2
3
4
5
6
7
If you have a servo in any of the first 8 connections (nearest board connection end) you servo should move back and forth a couple of times.
At this point although we may not understand the sketch we know the board and servos work.
Example 1: PCA9685RailCrossingV3.ino
Click to Download code: PCA9685RailCrossingV3.ino
In this version a number of functions have been added from the tutorial on the DY-SV5W MP3 Player
My barrier sound track is track 6 on my SD card, please change this value for your own sound.
Pressing the button closes the barriers, releasing the button raises them. The switch could be changed for a block detector or some other kind of sensor.
Software Serial was required as I built this on an Uno and I control the DY-SV5W using serial communication.
For other boards Serial1 should be used instead.
/* PCA9685RailCrossingV3
08/01/2024
Sound and Button Control Added
Sound provide by DY-SV5W MP3 player tutorial at:
https://www.digitaltown.co.uk/components18DYSV5W.php
Railway Crossing Sketch
PCA9685 board for servos...2 gate or 4 gate
PCA9685 board for LED's.... orange static, red flashing
Software Serial pins 10-11
Pin 9 Button press to start/release to stop
*/
#include "SoftwareSerial.h"
#include "Wire.h"
#include "Adafruit_PWMServoDriver.h"
//PCA 9685 settings
//Using the address as this sketch uses multiple PCA9685 boards
Adafruit_PWMServoDriver servoBoard = Adafruit_PWMServoDriver(0x40);//Address found from I2C scanner
Adafruit_PWMServoDriver LEDBoard = Adafruit_PWMServoDriver(0x46);//Address found from I2C scanner
#define USMIN 600 // This is the rounded 'minimum' microsecond length based on the minimum pulse of 150
#define USMAX 2400 // This is the rounded 'maximum' microsecond length based on the maximum pulse of 600
#define SERVO_FREQ 50 // Analog servos run at ~50 Hz updates
//end pca9685 settings
unsigned long currentMillis;//Keeps track of time in milliseconds for all timing
unsigned long triggerMillis;
unsigned long ledTimer;//stores time in millis for tracking events
byte ledState = 0;//Stores the current state of the system
byte currentledState = 0;// what is the current state
byte flashState;//is flash on or off
unsigned long gateServoTimer;
byte gateState;
unsigned long servoMovementTimer;
int servoPos[4][2];//[4 servos 0-3 on servo board][target pos, actual pos]
//software serial
SoftwareSerial mySerial(10, 11); // RX, TX
//DY-SV5W MP3 player
byte commandLength;
byte command[5];
int checkSum = 0;
int trackNum = 6;//track number on SD card
//Button
const int buttonPin = 9;//button on this pin with pull down resistor 4.7k
//sets the position of the servo in degrees.
void setServoPos(int servo, int pos) {
//This first bit of code makes sure we are not trying to set the servo outside of limits
int sendPos;
if (pos > 179) {
pos = 179;
}
if (pos < 0) {
pos = 0;
}
sendPos = USMIN + ((USMAX - USMIN) / 180 * pos);
if (servo > -1 && servo < 16) { //only try to move valid servo addresses
servoBoard.writeMicroseconds(servo, sendPos);
}
}
//This would normally be triggered by sensors/buttons/dcc control
//Using a timer just for demo purposes.
void gateTrigger() {
int buttonState = digitalRead(buttonPin);
//gate closing trigger when button is pressed
if (buttonState > 0 && ledState < 1) {
ledState = 1;
Serial.println("Trigger Close");
}
//gate opening trigger
//when button is released gates open.
if (gateState < 2 && ledState == 5 && buttonState == 0) { //
Serial.println("Trigger Open");
// triggerMillis = currentMillis + 10000;//reset timer
gateState = 2;
}
}
//controls movement and LEDs depending on led state
void ledControl() {
int q;
switch (ledState) {
case 1://system starting...set lights to orange for 3 seconds
if (currentledState < 1) {
currentledState = 1;//set the current state
Serial.println("Orange On");
for (int q = 0; q < 4; q++) {
LEDBoard.setPWM(q, 0, 4095);//turn Orange on full brightness
}
for (int q = 12; q < 16; q++) {
LEDBoard.setPWM(q, 0, 4095);//turn red barrier lights on
}
ledTimer = currentMillis;
ledState = 2;
Serial.println(ledState);
//start sound
playTrack(trackNum);//Crossing sound is track 6 on my SD Card
}
break;
case 2://Reds on orange off
if (currentMillis - ledTimer >= 3000) {
Serial.println("Reds on orange off 2");
for (q = 4; q < 12; q++) {
LEDBoard.setPWM(q, 0, 4095);//turn Reds on full brightness
}
for (q = 0; q < 4; q++) {
LEDBoard.setPWM(q, 0, 4096);//turn Orange off
}
ledTimer = currentMillis;
ledState = 3;
Serial.println(ledState);
}
break;
case 3://Reds off
if (currentMillis - ledTimer >= 1500) { //0.5 second on before turning off
Serial.println("Reds off 3");
for (q = 4; q < 12; q++) {
LEDBoard.setPWM(q, 0, 4096);//turn Reds off
}
ledTimer = currentMillis;
ledState = 4;
}
break;
case 4://Reds on
if (currentMillis - ledTimer >= 500) { //0.5 second on before turning on
Serial.println("Reds on 4");
for (q = 4; q < 12; q++) {
LEDBoard.setPWM(q, 0, 4095);//turn Reds on full brightness
}
ledState = 5;
gateState = 1;
gateServoTimer = currentMillis;
triggerMillis = currentMillis;
}
break;
case 5://Reds Flashing
if (currentMillis - ledTimer >= 500) { //0.5 secs on before turning on
ledTimer = currentMillis;
if (flashState > 0) {
for (q = 4; q < 8; q++) {
LEDBoard.setPWM(q, 0, 4095);//turn Reds on full brightness
}
for (q = 8; q < 12; q++) {
LEDBoard.setPWM(q, 0, 4096);//turn Reds off
}
flashState = 0;
} else {
for (q = 4; q < 8; q++) {
LEDBoard.setPWM(q, 0, 4096);//turn Reds off
}
for (q = 8; q < 12; q++) {
LEDBoard.setPWM(q, 0, 4095);//turn Reds on full brightness
}
flashState = 1;
}
}
break;
case 6://turn all LED's off... before barrier is fully down
for (q = 0; q < 16; q++) {
LEDBoard.setPWM(q, 0, 4096);//everything off;
}
currentledState = 0;
ledState = 0;
break;
default:
break;
}
}
//Works through 3 different gate "states"
void servoControl() {
switch (gateState) {
case 1://lower barriers...train coming
if (currentMillis - gateServoTimer >= 2000) {
for (int q = 0; q < 2; q++) {//clockwise barriers/gates
servoPos[q][0] = 89;
}
for (int q = 2; q < 4; q++) {//anti clockwise barriers gates
servoPos[q][0] = 89;
}
gateState = 0;
}
break;
case 2://raise barriers...train passed
//no timer, will trigger from external...train
for (int q = 0; q < 2; q++) {//clockwise barriers/gates
servoPos[q][0] = 0;
}
for (int q = 2; q < 4; q++) {//anti clockwise barriers gates
servoPos[q][0] = 179;
}
gateServoTimer = currentMillis;
gateState = 3;
break;
case 3://Turns the LED's off before the gate has fully lowered as per real thing.
//Serial.println(gateState);
if (currentMillis - gateServoTimer >= 2500) { //wait 1 secs while gate raises
gateState = 0;
ledState = 6;//turn leds off
stopTrack();//stop barrier sounds
triggerMillis = currentMillis;//reset trigger timer
}
break;
default:
break;
}
}
//this moves the servos to the value they have been targetted with
//but at a reduced speed to match the real thing
void servoMovement() {
int q;
if (currentMillis - servoMovementTimer >= 50) { //0.05 sec timin
servoMovementTimer = currentMillis;
for (q = 0; q < 4; q++) { //work through the 4 servos
if (servoPos[q][0] > servoPos[q][1]) { //if the target is higher angle
servoPos[q][1]++;//increment by 1
setServoPos(q, servoPos[q][1]);//send the new value
}
if (servoPos[q][0] < servoPos[q][1]) { //if the target is smaller angle
servoPos[q][1]--;//decrease by 1
setServoPos(q, servoPos[q][1]);//send the new value
}
}
}
}
//DY-SV5W MP3 player functions
//May need to be selected after putting into random mode
void stopTrack() {
command[0] = 0xAA;//first byte says it's a command
command[1] = 0x04;
command[2] = 0x00;
command[3] = 0xAE;
commandLength = 4;
sendCommand();
}
//play selected track
void playTrack(int soundTrack) {
//select track
//Serial.print("soundTrack: ");
//Serial.println(soundTrack);
command[0] = 0xAA;//first byte says it's a command
command[1] = 0x07;
command[2] = 0x02;
command[3] = highByte(soundTrack);//snh...track HIGH bit
command[4] = lowByte(soundTrack);//SNL... track low bit
checkSum = 0;
for (int q = 0; q < 5; q++) {
checkSum += command[q];
}
command[5] = lowByte(checkSum);//SM check bit... low bit of the sum of all previous values
commandLength = 6;
sendCommand();
}
//sets the device volume...0 - 30
void playbackVolume(int vol) {
if (vol > 30) { //check within limits
vol = 30;
}
command[0] = 0xAA;//first byte says it's a command
command[1] = 0x13;
command[2] = 0x01;
command[3] = vol;//volume
checkSum = 0;
for (int q = 0; q < 4; q++) {
checkSum += command[q];
}
command[4] = lowByte(checkSum);//SM check bit... low bit of the sum of all previous values
commandLength = 5;
sendCommand();
}
//sends the command to the DY-SV5W
void sendCommand() {
int q;
for (q = 0; q < commandLength; q++) {
mySerial.write(command[q]);
Serial.print(command[q], HEX);
}
Serial.println("End");
}
void setup() {
Serial.begin(9600);
Serial.println("PCA9685RailCrossingV3");
servoBoard.begin();
servoBoard.setOscillatorFrequency(27000000);
servoBoard.setPWMFreq(SERVO_FREQ); // Analog servos run at ~50 Hz updates
LEDBoard.begin();//start the PCA9685 for the station building
LEDBoard.setPWMFreq(1600); // This is the maximum PWM frequency and suited to LED's
delay(10);//let the above values take effect
//make sure everything is off
for (int q = 0; q < 16; q++) {
LEDBoard.setPWM(q , 0, 4096);//turn Orange on full brightness
}
//servos in start position
for (int q = 0; q < 2; q++) {//clockwise barriers/gates
setServoPos(q, 0);
servoPos[q][0] = 0;//target
servoPos[q][1] = 0;//actual
}
for (int q = 2; q < 4; q++) {//anti clockwise barriers gates
setServoPos(q, 179);
servoPos[q][0] = 179;//target
servoPos[q][1] = 179;//actual
}
//button
pinMode(buttonPin, INPUT);
//software serial
mySerial.begin(9600);
delay(100);
//DY-SV5W set up
playbackVolume(17);//sets volume to lvl 17
stopTrack();//stop barrier sounds
}
void loop() {
currentMillis = millis();//get current time since board started in milliseconds
gateTrigger();//function that checks if the gate should be moving...this would usually be reading sensors/buttons
ledControl();//controls the leds
servoControl();//servo movement/timing control
servoMovement();//deals with speed of movement...sweep at controlled speed
}
Additional Resource Links
Arduino and PCA9685 Model Railway Level Crossing Servo Barriers and LED Lights
DY-SV5W MP3 Player 15/12/2023
#55 Multiple PCA9685 PWM Servo Boards with servos and LED's 05/01/2024
PCA9685 PWM Servo Board 27/12/2023
Lesson 7: delay() v's millis(), controlling timing of programs 23/07/2021
State Machine Example based around model railway requirements 08/03/2023
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