I bought RF433Mhz set of STX882 and SRX882 and I have created RF-OT project with the code examples of scanner, tester and traffic light (semafor) system of sender with buttons and traffic light model with leds for toys cars etc. .
Here is my second RF433MHz project for telemetry with temperature, humidity and air pressure sensor BME280.
Both these my projects are based on RF library rc-switch from Github. Next info is in schetches for sender with RF module STX882 and NodeMcu V1.0 (V2) and receiver with RF module STX882 and Arduino Nano clone.
Here is sketch for sending of data from BME280 sensor with RF433MHz technology
Multifunction sensor BME280 for measuring
temperature, humidity and air pressure :
//RF-433MHz-STX882-BME280-sender
/*
Sketch for sending of data from BME280 sensor with RF433MHz technology
Multifunction sensor BME280 for measuring
temperature, humidity and air pressure is used
BME280 project details were addapted
from https://randomnerdtutorials.com by Riu Santos
Data are coupled with code for specification of different data
Example : specialised code for temperature is here set to 10 000 000
and to this code is added temperature (example) 23.45 * 100 = 2345
if temperature < 0 , the special code is set to 11 000 000
special code for humidity is set to 12 000 000
special code for air press is set to 13 000 000
This RF433 MHz application is based on library and examples
from https://github.com/sui77/rc-switch/
Reprogrammed by PavelOu
rewrited from RF-433MHz-STX882-BME280-sender-po-5
version of NodeMcu V1.0 (V2)
*/
// RF 433 library
#include <RCSwitch.h>
//Adafruit library
#include <Wire.h>
#include <Adafruit_BME280.h>
#include <Adafruit_Sensor.h>
String sketchName = "RF-433MHz-STX882-BME280-sender.ino";
const int ledPin = D3;
const int txPin = D5;
byte protocolNr = 2;
long int specialCode = 10000000;
byte nrBits = 32;
int intervalDat = 100; // ms
long int dataInt = 0;
byte dataMode = 0;
char markRx = 0;
bool status;
float temp = 23.45; // examples
float hump = 54.56;
float presp = 1021.89 ;
int timeRep = 30; //time for repeating of measuring in sec
int timeStep = 1;
bool i2cOn = false;
long int dataPom;
Adafruit_BME280 bme; // I2C => SCL = D1, SDA = D2
//Adafruit_BME280 bme(BME_CS); // hardware SPI
//Adafruit_BME280 bme(BME_CS, BME_MOSI, BME_MISO, BME_SCK); // software SPI
#define SEALEVELPRESSURE_HPA (1013.25)
// creating objekt senderRFe from library
RCSwitch senderRF = RCSwitch();
void printValues() //for test only
{
Serial.print("Temperature = ");
Serial.print(bme.readTemperature());
Serial.println(" *C");
Serial.print("Humidity = ");
Serial.print(bme.readHumidity());
Serial.println(" %");
//Convert temperature to Fahrenheit
Serial.print("Temperature = ");
Serial.print(1.8 * bme.readTemperature() + 32);
Serial.println(" *F");
Serial.print("Pressure = ");
Serial.print(bme.readPressure());
Serial.println(" Pa");
Serial.print("Pressure = ");
Serial.print(bme.readPressure() / 100.0F);
Serial.println(" hPa");
Serial.print("Approx. Altitude = ");
Serial.print(bme.readAltitude(SEALEVELPRESSURE_HPA));
Serial.println(" m");
}
void setup()
{
Serial.begin(9600);
while (!Serial)
{
delay(1000);
}
pinMode(ledPin,OUTPUT); // this led signalised RF transmission
digitalWrite(ledPin,HIGH);
delay(1000);
digitalWrite(ledPin,LOW);
Serial.println();
Serial.println(sketchName);
Serial.println("RF-OT 433 Mhz sender is starting ...");
// default settings
// (you can also pass in a Wire library object like &Wire2)
status = bme.begin(0x76);
//status = true; //for test without BME280 sensor
if (!status)
{
Serial.println("Could not find a valid BME280 sensor, check wiring!");
}
else
{
printValues(); //BME280 test
}
temp = 23.45; //for test only
// optional set of protocol on nr.2 //must be the some in the receiver
// senderRF.setProtocol(2);
// optional set of protocol nr.5
// senderRF.setRepeatTransmit(5); //here not used
protocolNr = 2;
Serial.print("Protocol: ");
Serial.println(protocolNr);
//testData = 22;
//Serial.print("Tested data: ");
//Serial.println(testData);
specialCode = 10000000;
Serial.print("special data set: ");
Serial.println(specialCode);
nrBits = 32;
Serial.print("Used nr of bits: ");
Serial.println(nrBits);
intervalDat = 100;
Serial.print("Interval dat: "); //optional
Serial.println(intervalDat);
markRx = 0;
//start with repetition in time 20 sec
timeRep = 20;
dataMode = 2;
senderRF.setProtocol(protocolNr);
// start of sending on txPin
senderRF.enableTransmit(txPin);
}
void loop()
{
if (dataMode == 0)
{
Serial.println();
Serial.println(sketchName);
Serial.println("New settings:");
Serial.println("A = data BME only, E = RF data BME, Tint = time for repeting");
dataMode = 1;
markRx = 0;
digitalWrite(ledPin,LOW); // turn the LED
}
if (Serial.available())
{
markRx = Serial.read();
Serial.print("choosed: ");
Serial.println(markRx);
timeRep = 0;
Serial.flush();
if ( markRx == 65 ) // A
{
Serial.println("Data BME");
//digitalWrite(ledPin, HIGH); // turn the LED on
printValues();
dataMode = 0;
}
/* this section is prepared for tests only
if ( markRx == 66 ) // B
{
String Bstring = Serial.readString();
Bstring.trim();
nrBits = Bstring.toInt();
Serial.print("Bits: ");
Serial.println(nrBits);
dataMode = 0;
}
if ( markRx == 67 ) // C
{
String Cstring = Serial.readString();
Cstring.trim();
specialCode = Cstring.toInt();
Serial.print("Special code: ");
Serial.println(specialCode);
dataMode = 0;
}
if ( markRx == 68 ) // D
{
// reading end command for sending - example 101 for set on green Led
String textToSend = Serial.readString();
dataInt = textToSend.toInt();
Serial.print("Sending Int Data: ");
Serial.println(dataInt);
temp = dataInt / 100.0;
//digitalWrite(ledPin, HIGH); // turn the LED on
dataMode = 2;
}
if ( markRx == 77 ) // M
{
// reading end command for sending - example 101 for set on green Led
String textToSend = Serial.readString();
dataInt = textToSend.toInt();
Serial.print("Sending Int Data with minus: ");
Serial.println(dataInt);
temp = - dataInt / 100.0;
digitalWrite(ledPin, HIGH); // turn the LED off
dataMode = 2;
}
if (markRx == 80) // P
{
String Pstring = Serial.readString();
Pstring.trim();
protocolNr = Pstring.toInt();
Serial.print("Protocol: ");
Serial.println(protocolNr);
senderRF.setProtocol(protocolNr);
dataMode = 0;
}
*/
if (markRx == 69) // E
{
Serial.println("Data BME send by RF");
//digitalWrite(ledPin, HIGH); // turn the LED on
dataMode = 2;
}
if (markRx == 84) // T
{
String Tstring = Serial.readString();
Tstring.trim();
timeRep = Tstring.toInt();
Serial.print("Time for repeating: ");
Serial.print(timeRep);
Serial.println(" in sec");
senderRF.setProtocol(protocolNr);
if (timeRep>0)
{
dataMode = 2;
timeStep = 0;
}
else
{
dataMode = 0;
Serial.println("time zero ??");
}
}
markRx = 0;
Serial.flush();
}
if (dataMode == 2 )
{
//start of measuring data and RF transmission
digitalWrite(ledPin,HIGH);
Serial.print("Temperature = ");
if (status)
{
temp = bme.readTemperature();
}
Serial.print(temp);
Serial.println(" *C");
if (temp > 0)
{
specialCode = 10000000;
dataPom = temp * 100; // dataPom = 23.45 * 100 = 2345
}
else
{
specialCode = 11000000;
dataPom = (-1) * temp * 100; // dataPom = -1 * - 23.45 * 100 = 2345
}
//dataPom = temp * 100; // dataPom = 23.45 * 100 = 2345
Serial.print("dataPom = ");
Serial.println(dataPom);
dataPom = specialCode + dataPom; //10000000 + 2345 = 10002345
Serial.print("specialCode + dataPom = ");
Serial.println(dataPom); //data are prepared for RF transmission
senderRF.setProtocol(protocolNr);
senderRF.send(dataPom,nrBits); // data are transfered
//back recounting (in receiver) example:
//dataResult = dataPom - specialCode = 10234500 - 10000000 = 234500
//dataPom = dataPom - dataResult = 10234500 - 234500 = 10000000
//dataUnit = dataPom / 1000000 = 10000000 / 1000000 = 10
//dataUnit = 10 => Unit is plus temp
//dataUnit = 11 => Unit is minus temp etc.
//temp = dataResult / 10000 = 234500 /10000 = 23.45 *C
// if dataUnit == 11 => temp = -23.45
// pause before preparing and transmitting of next data
delay(intervalDat);
Serial.print("Humidity = ");
if (status)
{
hump = bme.readHumidity();
}
Serial.print(hump);
Serial.println(" %");
specialCode = 12000000;
dataPom = hump * 100; // dataPom = 43.45 * 100 = 4345
Serial.print("dataPom = ");
Serial.println(dataPom);
dataPom = specialCode + dataPom; //12000000 + 4345 = 12004345
Serial.print("specialCode + dataPom = ");
Serial.println(dataPom);
senderRF.setProtocol(protocolNr);
senderRF.send(dataPom,nrBits);
delay(intervalDat);
Serial.print("Pressure in Pa = ");
if (status)
{
presp = bme.readPressure();
}
Serial.println(presp);
Serial.print("Pressure in hPa= ");
Serial.print( presp / 100.0);
Serial.println(" hPa");
specialCode = 13000000;
dataPom = presp * 10; // dataPom = 10216.78 * 10 = 102167 in deko Pa
Serial.print("dataPom = ");
Serial.println(dataPom);
dataPom = specialCode + dataPom; //13000000 + 102167= 13102167
Serial.print("specialCode + dataPom = ");
Serial.println(dataPom);
senderRF.setProtocol(protocolNr);
senderRF.send(dataPom,nrBits);
/* not used
Serial.print("Approx. Altitude = ");
Serial.print(bme.readAltitude(SEALEVELPRESSURE_HPA));
Serial.println(" m");
*/
// pause before new transmitting of data
delay(1000);
digitalWrite(ledPin,LOW);
if (timeRep == 0)
{
//delay(intervalDat);
dataMode = 0;
}
else
{
Serial.print("Time: ");
Serial.print(timeRep);
Serial.println(" sec is starting ...");
timeStep = 0;
dataMode = 3;
}
} // end of dataMode = 2
if (dataMode == 3)
{
timeStep += 1;
if (timeStep == timeRep)
{
timeStep = 0;
Serial.println("*");
Serial.print("Time: ");
Serial.print(timeRep);
Serial.println(" is on !");
dataMode = 2;
}
else
{
Serial.print(timeStep);
Serial.print(",");
delay(1000);
}
} // end of dataMode = 3
}
