ESP32 stops sending data via wifi after a while - c++

Question

I am using an esp32 to send some environmental data, such as temperature, humidity, pressure, pm2.5, and TVOV to a thinkspeak server. This works sometimes for a few hours and then it suddenly stops sending data. It also seems to be a bit random on when it stops. Sometimes it works just a few minutes and sometimes much longer. My code is probably is a great mess as I combined the codes from different sensors. Can anybody check the code and maybe see what my ESP32 suddenly stops sending data?
Code:
#include <WiFi.h>
#include <Wire.h>
#include "Adafruit_SGP30.h"
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#define LENG 31 //0x42 + 31 bytes equal to 32 bytes
unsigned char buf[LENG];
Adafruit_SGP30 sgp;
int PM01Value=0; //define PM1.0 value of the air detector module
int PM2_5Value=0; //define PM2.5 value of the air detector module
int PM10Value=0; //define PM10 value of the air detector module
float h, t, p, pin, dp;
char temperatureFString[6];
char dpString[6];
char humidityString[6];
char pressureString[7];
char pressureInchString[6];
/* return absolute humidity [mg/m^3] with approximation formula
* #param temperature [°C]
* #param humidity [%RH]
*/
uint32_t getAbsoluteHumidity(float t, float h) {
//approximation formula from Sensirion SGP30 Driver Integration chapter 3.15
const float absoluteHumidity = 216.7f * ((h / 100.0f) * 6.112f * exp((17.62f * t) / (243.12f + t)) / (273.15f + t)); // [g/m^3]
const uint32_t absoluteHumidityScaled = static_cast<uint32_t>(1000.0f * absoluteHumidity); // [mg/m^3]
return absoluteHumidityScaled;
}
char checkValue(unsigned char *thebuf, char leng)
{
char receiveflag=0;
int receiveSum=0;
for(int i=0; i<(leng-2); i++){
receiveSum=receiveSum+thebuf[i];
}
receiveSum=receiveSum + 0x42;
if(receiveSum == ((thebuf[leng-2]<<8)+thebuf[leng-1])) //check the serial data
{
receiveSum = 0;
receiveflag = 1;
}
return receiveflag;
}
int transmitPM01(unsigned char *thebuf)
{
int PM01Val;
PM01Val=((thebuf[3]<<8) + thebuf[4]); //count PM1.0 value of the air detector module
return PM01Val;
}
//transmit PM Value to PC
int transmitPM2_5(unsigned char *thebuf)
{
int PM2_5Val;
PM2_5Val=((thebuf[5]<<8) + thebuf[6]);//count PM2.5 value of the air detector module
return PM2_5Val;
}
//transmit PM Value to PC
int transmitPM10(unsigned char *thebuf)
{
int PM10Val;
PM10Val=((thebuf[7]<<8) + thebuf[8]); //count PM10 value of the air detector module
return PM10Val;
}
String apiKey = "6HNZHJJA9KD2PM43";
// replace with your routers SSID
const char* ssid = "XXX";
const char* password = "XXX";
const char* server = "api.thingspeak.com";
WiFiClient client;
Adafruit_BME280 bme; // I2C
void setup() {
Serial.begin(9600);
delay(10);
Serial.println();
Wire.begin();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
// Printing the ESP IP address
Serial.println(WiFi.localIP());
if (!bme.begin(0x76))
{
Serial.println("Could not find a valid BME280 sensor, check wiring!");
while (1);
}
if (! sgp.begin()){
Serial.println("Could not find a valid SGP30 sensor, check wiring!");
while (1);
}
Serial.print("Found SGP30 serial #");
Serial.print(sgp.serialnumber[0], HEX);
Serial.print(sgp.serialnumber[1], HEX);
Serial.println(sgp.serialnumber[2], HEX);
// If you have a baseline measurement from before you can assign it to start, to 'self-calibrate'
//sgp.setIAQBaseline(0x8E68, 0x8F41); // Will vary for each sensor!
}
int counter = 0;
void loop() {
// If you have a temperature / humidity sensor, you can set the absolute humidity to enable the humditiy compensation for the air quality signals
sgp.setHumidity(getAbsoluteHumidity(t, h));
if (! sgp.IAQmeasure()) {
Serial.println("Measurement failed");
return;
}
Serial.print("TVOC "); Serial.print(sgp.TVOC); Serial.print(" ppb\t");
Serial.print("eCO2 "); Serial.print(sgp.eCO2); Serial.println(" ppm");
if (! sgp.IAQmeasureRaw()) {
Serial.println("Raw Measurement failed");
return;
}
counter++;
if (counter == 20) {
counter = 0;
uint16_t TVOC_base, eCO2_base;
if (! sgp.getIAQBaseline(&eCO2_base, &TVOC_base)) {
Serial.println("Failed to get baseline readings");
return;
}
Serial.print("****Baseline values: eCO2: 0x"); Serial.print(eCO2_base, HEX);
Serial.print(" & TVOC: 0x"); Serial.println(TVOC_base, HEX);
}
h = bme.readHumidity();
t = (bme.readTemperature()-2);
dp = t-0.36*(100.0-h);
p = bme.readPressure()/100.0F;
pin = 0.02953*p;
dtostrf(t, 5, 1, temperatureFString);
dtostrf(h, 5, 1, humidityString);
dtostrf(p, 6, 1, pressureString);
dtostrf(pin, 5, 2, pressureInchString);
dtostrf(dp, 5, 1, dpString);
Serial.print("Temperature = ");
Serial.println(temperatureFString);
Serial.print("Humidity = ");
Serial.println(humidityString);
Serial.print("Pressure = ");
Serial.println(pressureString);
if(Serial.find(0x42)){ //start to read when detect 0x42
Serial.readBytes(buf,LENG);
if(buf[0] == 0x4d){
if(checkValue(buf,LENG)){
PM01Value=transmitPM01(buf); //count PM1.0 value of the air detector module
PM2_5Value=transmitPM2_5(buf);//count PM2.5 value of the air detector module
PM10Value=transmitPM10(buf); //count PM10 value of the air detector module
}
}
}
static unsigned long OledTimer=millis();
if (millis() - OledTimer >=1000)
{
OledTimer=millis();
}
Serial.print("PM1.0: ");
Serial.print(PM01Value);
Serial.println(" ug/m3");
Serial.print("PM2.5: ");
Serial.print(PM2_5Value);
Serial.println(" ug/m3");
Serial.print("PM10 : ");
Serial.print(PM10Value);
Serial.println(" ug/m3");
Serial.println();
Serial.println("...............................................");
if (client.connect(server,80)) // "184.106.153.149" or api.thingspeak.com
{
String postStr = apiKey;
postStr +="&field1=";
postStr += String(temperatureFString);
postStr +="&field2=";
postStr += String(humidityString);
postStr +="&field3=";
postStr += String(pressureString);
postStr +="&field4=";
postStr += String(PM01Value);
postStr +="&field5=";
postStr += String(PM2_5Value);
postStr +="&field6=";
postStr += String(PM10Value);
postStr +="&field7=";
postStr += String(sgp.eCO2);
postStr +="&field8=";
postStr += String(sgp.TVOC);
postStr += "\r\n\r\n";
client.print("POST /update HTTP/1.1\n");
client.print("Host: api.thingspeak.com\n");
client.print("Connection: close\n");
client.print("X-THINGSPEAKAPIKEY: "+apiKey+"\n");
client.print("Content-Type: application/x-www-form-urlencoded\n");
client.print("Content-Length: ");
client.print(postStr.length());
client.print("\n\n");
client.print(postStr);
}
delay(16000);
client.stop();
}