Use RF 433MHz Transmitter/Receiver to transmit parking availability data

Overview

This is the third tutorial for Smart Parking Philadelphia(SPP), which is the final project of our team for Sensing the City course taught by Allison Lassiter in Upenn.

In this tutorial, I will simulate the changes in street parking spots generated by traffic, transmit and receive this data by RF 433MHz Transmitter/Receiver. Please refer to my teammate’s tutorial for details on how to get street parking data: https://www.sensingthecity.com/induction-loop-detector-for-counting-vehicles-entering-and-leaving-a-section-of-street/

The major steps are:

Solder pin headers
Prepare your Arduino IDE to communicate with the RF 433MHz Transmitter/Receiver
Wire the circuits
Write code to control the transmitter and receiver boards

Advantage & Resource

Why RF 433MHz ?

Reference: https://homey.app/en-ie/wiki/433-mhz/

Low cost
Good signal, works even when obscured by entities
Easy to operate

In this tutorial, the coding part was mainly from: https://randomnerdtutorials.com/rf-433mhz-transmitter-receiver-module-with-arduino/

For how to convert the data into integars, I also asked for some instructions from the arduino forum: https://forum.arduino.cc/t/transmitting-an-int-over-433mhz-rf-transmitter-reciever/586222/2

For the visualization with RGB LED part, it is in my teammate Hongyi’s tutorial:

https://www.sensingthecity.com/use-rf-433mhz-receiver-and-rgb-led-to-visualize-street-parking-availability/

Parts Needed

RF 433MHz :

Working distance: within 500 feets wirelessly

2. Large breadboard (or two small breadboards)

3. Arduino Uno *2

3. RGB LED

4. Male To Female Jumper Wires

Step by Step Tutorial

1. Transmit Data

The first part is to transmit the parking data. In my section I will use numbers to simulate the real street parking number, and how to get them will be available in my teammates’ tutorial. Wire the transmitter module to the Arduino by following the next schematic diagram.

For this part, we should download a library called RadioHead and install it.

The transmit data needs one computer and an arduino Uno. The code is in part 4, transmit code.

Transmitter Circuit
(Source: https://randomnerdtutorials.com/rf-433mhz-transmitter-receiver-module-with-arduino/ )

2. Receiving Data

Wire the receiver module to another Arduino by following the next schematic diagram.

The receiver circuit will receive the parking data and then visualize it. The receiving data also needs one computer and an arduino Uno. By this step, we can get the parking data. The code for this part is in part 4, receive code.

Receive Circuit (Source: Self-drawn by the author)

3. Visualization

Specific Parking Availability

The visualization part was divided into two parts. For the first part, we can use serial monitor to show the specific number of parking spots in the street. However, it is still a little bit hard for drivers to make a decision within few seconds. So we tried to use different colors of LED to visualize the availability of parking spots.

Visualize with RGB LED

Then we can use the RGB LED to visualize the availability of parking spots in the street. This part will be explain in detail in my teammate’s part.

color of the LED will change by the availability of parking spots

4. Write code to control the transmitter and receiver boards

Transmit Code

/* Jingyi Cai;  04/01/2023 
  This is the part for transmit data.
  Parking data comes from Changhao and Hang's tutorial.
— https://randomnerdtutorials.com/rf-433mhz-transmitter-receiver-module-with-arduino/

*/

// 1. Including the library with the statement
#include <RH_ASK.h>
#include <SPI.h> // Not actually used but needed to compile

RH_ASK driver;

// 2. define the pins related to the RGB LED
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);	  // Debugging only
  if (!driver.init())
    Serial.println("init failed");
}

uint8_t data = 1; //set the number of the parking space, and how to get the parking data was in my teamates' tutorial.

// 3. put your setup code here, to run once:
void loop() {
  
  driver.send(&data, 1); 
  driver.waitPacketSent();
  delay(1000);
}

/* Jingyi Cai; 04/01/2023

This is the part for transmit data.

Parking data comes from Changhao and Hang's tutorial.

— https://randomnerdtutorials.com/rf-433mhz-transmitter-receiver-module-with-arduino/

// 1. Including the library with the statement

#include <RH_ASK.h>

#include <SPI.h> // Not actually used but needed to compile

RH_ASK driver;

// 2. define the pins related to the RGB LED

void setup() {

// put your setup code here, to run once:

Serial.begin(9600); // Debugging only

if (!driver.init())

Serial.println("init failed");

}

uint8_t data = 1; //set the number of the parking space, and how to get the parking data was in my teamates' tutorial.

// 3. put your setup code here, to run once:

void loop() {

driver.send(&data, 1);

driver.waitPacketSent();

delay(1000);

}

Receive Code

/* Hongyi Li(LED part), Jingyi Cai(transmit & receive part);  04/01/2023 
 “This project extends how to use RF 433MHz Transmitter/Receiver Module With Arduino to transfer data from two arduinos
  Then,  use RGB LED to visiualize the availability of parking space. The coding part was done collaborately, but two
  tutorials will have a different focus
  Parking data comes from Changhao and Hang's tutorial.
— https://randomnerdtutorials.com/rf-433mhz-transmitter-receiver-module-with-arduino/

*/

// 1. Including the library with the statement

#include <RH_ASK.h>
#include <SPI.h> // Not actualy used but needed to compile

RH_ASK driver;

// 2. define the pins related to the RGB LED
const int RED_PIN = 3;
const int GREEN_PIN = 5;
const int BLUE_PIN = 6;

// 3. put your setup code here, to run once:
void setup()
{
    Serial.begin(9600);	// Debugging only
    if (!driver.init())
         Serial.println("init failed");
    pinMode(RED_PIN, OUTPUT);
    pinMode(GREEN_PIN, OUTPUT);
    pinMode(BLUE_PIN, OUTPUT);
}

// 4. Run repeatedly
void loop()
{
    uint8_t buf[2];
    uint8_t parking = (buf[0]);    // Get the number of parking in int form
    uint8_t buflen = sizeof(buf)
   


    if (driver.recv(buf, &buflen)) // Non-blocking
    {
      int i;
      // Message with a good checksum received, dump it.
      Serial.print("Parking Space: ");
      Serial.println(*buf); // print the number of parking space
      showRGB(parking); // show the light for different availablity 
               
    }
}


// 5. Set the function of showRGB to visiualize the parking space 
void showRGB(uint8_t parking)
{
  int redIntensity;
  int greenIntensity;
  int blueIntensity;

  if (parking <= 2)          // turn on the Red light
  {
    redIntensity = 255;    
    greenIntensity = 0;        
    blueIntensity = 0;            
  }
  else if (parking > 2, parking <= 5)     // turn on the Yellow light
  {
    redIntensity = 255;                     
    greenIntensity = 27 ; 
    blueIntensity = 0;        
  }
  else // turn on the Green light
  {
    redIntensity = 0;        
    greenIntensity = 255;                  
    blueIntensity = 0;  // 
  }

  analogWrite(RED_PIN, redIntensity);
  analogWrite(BLUE_PIN, blueIntensity);
 analogWrite(GREEN_PIN, greenIntensity);
}

/* Hongyi Li(LED part), Jingyi Cai(transmit & receive part); 04/01/2023

“This project extends how to use RF 433MHz Transmitter/Receiver Module With Arduino to transfer data from two arduinos

Then, use RGB LED to visiualize the availability of parking space. The coding part was done collaborately, but two

tutorials will have a different focus

Parking data comes from Changhao and Hang's tutorial.

— https://randomnerdtutorials.com/rf-433mhz-transmitter-receiver-module-with-arduino/

// 1. Including the library with the statement

#include <RH_ASK.h>

#include <SPI.h> // Not actualy used but needed to compile

RH_ASK driver;

// 2. define the pins related to the RGB LED

const int RED_PIN = 3;

const int GREEN_PIN = 5;

const int BLUE_PIN = 6;

// 3. put your setup code here, to run once:

void setup()

{

Serial.begin(9600); // Debugging only

if (!driver.init())

Serial.println("init failed");

pinMode(RED_PIN, OUTPUT);

pinMode(GREEN_PIN, OUTPUT);

pinMode(BLUE_PIN, OUTPUT);

}

// 4. Run repeatedly

void loop()

{

uint8_t buf[2];

uint8_t parking = (buf[0]); // Get the number of parking in int form

uint8_t buflen = sizeof(buf)

if (driver.recv(buf, &buflen)) // Non-blocking

{

int i;

// Message with a good checksum received, dump it.

Serial.print("Parking Space: ");

Serial.println(*buf); // print the number of parking space

showRGB(parking); // show the light for different availablity

}

// 5. Set the function of showRGB to visiualize the parking space

void showRGB(uint8_t parking)

{

int redIntensity;

int greenIntensity;

int blueIntensity;

if (parking <= 2) // turn on the Red light

{

redIntensity = 255;

greenIntensity = 0;

blueIntensity = 0;

}

else if (parking > 2, parking <= 5) // turn on the Yellow light

{

redIntensity = 255;

greenIntensity = 27 ;

blueIntensity = 0;

}

else // turn on the Green light

{

redIntensity = 0;

greenIntensity = 255;

blueIntensity = 0; //

}

analogWrite(RED_PIN, redIntensity);

analogWrite(BLUE_PIN, blueIntensity);

analogWrite(GREEN_PIN, greenIntensity);

}

Congratulations! You’ve sensed, transmitted, received, and responded to stimuli using RF 433MHz Transmitter/Receiver!