How to insert into table in database after every 5 minutes using Real time clock module

Question

I have RTC module attached to arduino mega,

to calculate time difference of minutes I am getting minute from the RTC module

and checking if passed time is greater than 5 minutes then insert to MySQL table in database.

 int mint = util::getMinute();
 if (util::getMinute() - mint >= 5)
 {
 // inserting to sql database on mysql server
 INSERT_SQL = "";
 INSERT_SQL.concat("INSERT INTO arduinoSensorData.outTempLog (out_temperature) VALUES ('");
 INSERT_SQL.concat(tempInC);
 INSERT_SQL.concat("');");
 const char *mycharp = INSERT_SQL.c_str();
 delay(1000);
 if (!connected) {
 my_conn.mysql_connect(server_addr, 3306, user, password);
 connected = true;
 }
 else if (connected == true)
 {
 delay(500);
 Serial.print("Inserting : ");
 Serial.println(INSERT_SQL);
 Serial.println("Connection Successfull,inserting to database.");
 my_conn.cmd_query(mycharp);
 }
 else {
 Serial.println("Connection failed.");
 }
 mint = util::getMinute();
 }

the full code is here

• Gerben: Move int mint = util::getMinute(); outside the loop function. Otherwise util::getMinute() - mint will always be 0.
• uint128_t: Just a tip, you didn't specify what RTC you're using, but most RTCs have an internal alarm functionality that will trigger an alert when a specific time of day is reached. This allows you to eliminate the polling from your code, and even sleep in between the 5 mins, which can greatly improve your power consumption.
• Ciasto piekarz: Oh sweet I didn't knew that it's DS3231

Answer 1

int mint = util::getMinute();
if (util::getMinute() - mint >= 5)
{

Well, if mint is util::getMinute() then surely util::getMinute() - mint will always be 0.

I think you meant mint to be static, or a variable in the global scope.

• Ciasto piekarz: done that but I don't see database getting inserted even after making the change

Answer 2

So I figured it out myself and used millis instead.

in global declaration I did:

unsigned long sqlInsertInterval = 300000; // the repeat interval after 5 minutes

then initiate timer in setup method

 timer = millis(); // start timer

followed by below changes in the loop method.

void loop() {
 // perform sql insert after 5 minutes
 if ((millis() - timer) > sqlInsertInterval) {
 // timed out
 timer += sqlInsertInterval;// reset timer by moving it along to the next interval
 // inserting to sql database on mysql server
 INSERT_SQL = "";
 INSERT_SQL.concat("INSERT INTO arduinoSensorData.outTempLog (out_temperature) VALUES ('");
 INSERT_SQL.concat(tempInC);
 INSERT_SQL.concat("');");
 const char *mycharp = INSERT_SQL.c_str();
 if (!connected) {
 my_conn.mysql_connect(server_addr, 3306, user, password);
 connected = true;
 }
 else if (connected == true)
 {
 Serial.print("Inserting : ");
 Serial.println(INSERT_SQL);
 Serial.println("Connection Successfull,inserting to database.");
 my_conn.cmd_query(mycharp);
 }
 else {
 Serial.println("Connection failed.");
 }
 }
}