Splitting sketch in threads and classes

spike32
Posts: 2
Joined: Fri Oct 22, 2021 10:30 am

Splitting sketch in threads and classes

Postby spike32 » Thu Nov 25, 2021 3:35 pm

Hello everyone! I'm working on a quite complex and large skatch for my ESP32 and I'm dividing it into threads and classes, splitting everything in different files. For sake of simplicity I'm gonna show you just the idea of my project setup

For instance, I'm using a BME280 sensor to read temperature, humidity, and pressure values. Therefore, I created an header file called "bme280.h" and an associated cpp file called "bme280.cpp". Here's the content of the two files.

bme280.h

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#ifndef BME280_H
#define BME280_H

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>

#define SEALEVELPRESSURE_HPA (1013.25)

typedef struct {
  float temperature;
  float pressure;
  float humidity;
}bmeData;

class BME280_sensor {  
  public:
    BME280_sensor();
    bmeData readBmeData();

  private:
    Adafruit_BME280 bme;
};

#endif
bme280.cpp

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#include "bme280.h"

BME280_sensor::BME280_sensor() {
  bool status;
  
  status = bme.begin(0x76);  
  if (!status) {
    Serial.println("Could not find a valid BME280 sensor, check wiring!");
    // exit(0);
    while (1);
  }
  Serial.println("BME280 sensor correctly initialized!");
}

bmeData BME280_sensor::readBmeData() {
  bmeData bmeValues;

  bmeValues.temperature = bme.readTemperature();
  bmeValues.pressure = bme.readPressure() / 100.0F;
  bmeValues.humidity = bme.readHumidity();

  return bmeValues;
}
This is basically how I'm using every sensor.

Now, my .ino file is busy doing some other job, so I used the pthread library for creating a different thread in charge of reading sensors values. Hence, my .ino file, before doing its job, starts this thread, which I named mainThread. Here's an example:

file.ino

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#include <pthread.h>
#include "main.h"

void setup() {
  delay(1000);
  Serial.begin(115200);
  Serial.println("Serial initialized");

  pthread_t mainThreadRef;
  int mainValue;

  mainValue = pthread_create(&mainThreadRef, NULL, mainThread, (void*)true);

  if (mainValue) {
     Serial.println("Main thread error occured");
  }
}

void loop() {
  // Some other job
}
The main thread, instead, is implemented using a "main.h" file and a "main.cpp" file. Here's an example:

main.h

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#ifndef MAIN_H
#define MAIN_H

#include <Arduino.h>

void *mainThread();

#endif
main.cpp

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#include "main.h"
#include "bme280.h"

void *mainThread(void *firstIteration) {
  BME280_sensor bme;
  
  while (1) {
  	bmeData bmeValues = bme.readBmeData();
  	
  	Serial.println(bmeValues.temperature);
  	Serial.println(bmeValues.humidity);
  	Serial.println(bmeValues.pressure);
  	
  	delay(3000);
  }
}
Now, I wonder if this whole structure of the project is good, because I'm facing weird values reading, like temperature over 100 or pressure under 0, and some other weird stuff. To be more precise:

1) Is it "safe" to have a thread acting as the main thread doing all the jobs?
2) Is it good to have a different class for each sensor that I am using or does it interfere with sensor readings?

Thank you everyone for your help in advance!

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