Hi all, I am working on a project for which I want to connect various sensors to my arduino through serial communication and also I2C.
I wrote a little program (I am very new to programming) and it worked perfect for AHT21B humidity and temperature sensor connected to the SCL and SDA on my arduino, and a DHT22 humidity and temperature sensor connected to digital pins.
Now I recently bought a PCA9548A multiplexer to function as an I2C bus so that I can add another AHT21B sensor (they both have the same adress) and 2 BMP280 airpressure sensors that also both have the same adress.
I started with trying to connect both of the AHT21B sensors on channel 6 and 7. But I think something is going wrong. I do not get an error message, but while normally it would print all the data in CSV in my serial monitor (I then downloaded PLX-DAQ), right now it doesnt print anything in the serial monitor at all..
Can someone help me? I am very new so I think, something is going wrong with defining the sensors, or the multiplexer etc. I don't fully understand everything I wrote yet. (fyi, I know some code is grey, those are just ideas I had/ what I saw in tutorials but what I didnt use yet)
#include <LiquidCrystal.h> //LCD screen library
#include <DHT.h> //Temperature and Humidity sensor library
#include <Adafruit_AHTX0.h> //Adafruit library for the AHT21 sensor
#include <Wire.h> //Library to work with Inter-Integrated Circuit (I2C) Protocol
// initialize the library by associating any needed LCD interface pin with the arduino pin number it is connected to
LiquidCrystal lcd(12, 13, 8, 9, 10, 11); // parameters (rs, e, d4,d5,d6,d7)
// defining the pin for the DHT sensor
#define datapinDHT22 7 // Digital pin the DHT is connected to
#define DHTTYPE DHT22
DHT dht22(datapinDHT22, DHTTYPE); // Initialise DHT sensor as object
// defining objects for the AHT temp and humidity sensors
Adafruit_AHTX0 aht1;
Adafruit_AHTX0 aht2;
//#define Multiplier 0x00 //TCA9548A module I2C adress 0x00
// TCA9548A I2C channel 2 contains AHT21B_V1.1 0x38
// TCA9548A I2C channel 3 contains AHT21B_V1.1 0x38
//#define addr1 0x38 // AHT21B_V1.1 device 1
//#define addr2 0x38 // AHT21B_V1.1 device 2
// make custom temperature character for LCD
byte customChar[] = {
B01110,
B01010,
B01110,
B00000,
B00000,
B00000,
B00000,
B00000
};
unsigned long startMillis;
unsigned long currentMillis;
const unsigned long period = 1000; // 1000 milliseconds is 1 second. 60000 is 1 minute
float tempD;
float humidityD;
void setup() {
Wire.begin(); // start the Wire library for I2C
PCA9548A(7); // call for channel 7
aht1.begin(); // initialise temp and humid sensor 1
PCA9548A(6); // call for channel 6
aht2.begin(); // initialise temp and humid sensor 2
dht22.begin(); // setup the DHT to start measuring
lcd.begin(16, 2); // set up the LCD's number of columns and rows:
lcd.createChar(0, customChar); //Create the custom character defined above.
//Wire.begin(); // Enable I2C communication as master
startMillis = millis(); // Capture the start time
Serial.println("CLEARDATA"); // to clear the data before we send new data to excel
Serial.println("LABEL,Time, Minutes, temperature.a, humidity.a, temperature.d, humidity.d");
}
void PCA9548A(uint8_t bus) { // forms a switch for channels
Wire.beginTransmission(0x70); // adress of PCA9548A multiplexer;
Wire.write(1 << bus); // send byte to the selected bus
Wire.endTransmission();
}
void loop() {
currentMillis = millis(); //get the current "time" (Number of milliseconds since the program started)
int minutes = int(currentMillis / 60000);
sensors_event_t humidityA, tempA; //measure temp and humidity with AHT21B 1
aht1.getEvent(&humidityA, &tempA); //populate temp and humidity objects with fresh data
sensors_event_t humidityA2, tempA2; // measure temp and humidty with AHT21B 2
aht2.getEvent(&humidityA2, &tempA2);
tempD = dht22.readTemperature(); // measure temp with DHT
humidityD = dht22.readHumidity(); // measure humidity with DHT
// print data on LCD screen
lcd.setCursor(0, 0); //setting for first lcd row
lcd.print(String("T.d:") + String(tempD) + String(" C")); // Print temperature data to the LCD.
lcd.write(byte(0)); // write special character behind C
lcd.setCursor(0, 1); // setting second lcd row
lcd.print(String("RH.a:") + String(humidityD) + String("%")); // Print humidity data to the LCD
if (currentMillis - startMillis >= period) // test if period has elapsed
{ //Serial.p println(String("time, temperature.a, humidity.a"));
Serial.print("DATA,TIME,");
Serial.print(minutes); // TIME
Serial.print(",");
Serial.print(tempA.temperature); // temperature A form aht1
Serial.print(",");
Serial.print(humidityA.relative_humidity); // humidity A from aht1
Serial.print(",");
Serial.print(tempA2.temperature); // temperature A2 from aht2
Serial.print(",");
Serial.print(humidityA2.relative_humidity); // humidity A2 from aht2
Serial.print(tempD); // temperature d
Serial.print(",");
Serial.print(humidityD); // humidity d
Serial.println();
startMillis = currentMillis; //IMPORTANT to save the start time
}
}
