arduino credit card reader code example

Example: arduino sd card reader

/*Save temperature in SD/microSD card every hour with DS3231 + SD/microSD module + Arduinomodified on 15 Apr 2019by Mohammadreza Akbari @ Electropeakhttps://electropeak.com/learn/*/#include <SPI.h>#include <SD.h>#include <Wire.h>#include "Sodaq_DS3231.h"File myFile;DateTime now;int newHour = 0;int oldHour = 0;void save_temperature() {myFile = SD.open("temp.txt", FILE_WRITE);now = rtc.now();myFile.print(now.hour());myFile.print(":");myFile.print(now.minute());rtc.convertTemperature(); //convert current temperature into registersmyFile.print(",");myFile.println(rtc.getTemperature()); //read registers and save temperature on deg CmyFile.close();}void setup (){Wire.begin();rtc.begin();Serial.begin(9600);Serial.print("Initializing SD card...");if (!SD.begin(10)) {Serial.println("initialization failed!");while (1);}Serial.println("initialization done.");now = rtc.now();oldHour = now.hour();}void loop (){now = rtc.now();newHour = now.hour();if (oldHour != newHour) {save_temperature();oldHour = newHour;}}