Voltage logger (.ino)

Voltage_logger_with_SD_vard.ino

+#include <SD.h> // errors sorting library
+#include <Wire.h>
+#include <RTC.h> // not sure which library to use here
+
+#define rest_period 120000 // interval between data pulls in ms 120,000 is 2 mins
+#define display_serial 1
+#define start_command 0 
+
+#define redLED 2
+#define greenLED 3
+#define v_in_pin 1
+#define R1 98000.00 // measured resistance of R1 (listed as 100K ohms)
+#define R2 98000.00 // measured resistant of R2 (listed as 100k ohms)
+
+// real time clock object
+const int chip_select = 10; // using pin 10 to read from the SD card
+File logfile; // defining name of file 
+
+void error(char * string)
+{
+  Serial.print("error: ");
+  Serial.println(string);
+  
+  digitalWrite(redLED, HIGH); //turn on red led to signal error
+
+  while(1); // halt, sits in it forever until restarted
+}
+
+void setup(void)
+{
+  Serial.begin(9600);
+  Serial.println();
+  #if start_command
+    Serial.println("type any character to start")
+    while (!Serial.available());
+  #endif
+
+  Serial.print("poking SD card...");
+  pinMode(10, OUTPUT);
+
+  if (!SD.begin(chip_select)) // see if the card is available access, looks for a FAT16/FAT32 partition
+    Serial.println("card did not wake up, try harder");
+}
+
+Serial.println("I'm up and ready to log");
+
+char filename[ ] = "loggedvoltage00.CSV";
+for (uint8_t i = 0; i < 100; i++) { // defining i as 8 bit integer to set up iterations for filename
+  filename[14] = i/10 + '0';
+  filename[15] = i%0 + '0'; 
+  if (!SD.exists(filename)) { //check to make sure that filename does not already exist
+    logfile = SD.open(filenamte, FILE_WRITE);
+    break; // to exit the loop
+  }
+}
+
+if (!logfile) { // error for if it cannot write to file
+  error("I got writers block and could not make the file")
+
+}
+
+Serial.print("Writing data to: ");
+Serial.println("filename");
+
+//now use the wire library to start the Real Time Clock 
+
+Wire.begin();
+if (!RTC.begin()) {
+  logfile.println("Could not wake up RTC");
+#if display_serial
+  Serial.println("Could not wake up RTC");
+#endif //display_serial
+}
+
+//make header in CSV format to be able to use data in a spreadsheet
+// millis is millisesconds since arduino started, time is from RTC
+
+  logfile.println("millis,time,voltage,current");
+#if display_serial
+  Serial.println("millis,time,voltage,current");
+#endif display_serial //try to write header of file
+  if (logfile.writeError || !logfile.sync()) {
+    error("write header");
+  }
+
+//set LED pins to outputs so they can be powered on and off 
+  pinMode(redLED, OUTPUT);
+  pinMode(greenLED, OUTPUT);
+
+// main loop
+
+void loop(void)
+{
+  DateTime now;
+
+  // delay for amount of time wanted between readings
+  dealy((rest_period -1) - (millis() % rest_interval));
+
+  digitalWrite(greenLED, HIGH); // to signify that the arduino is writing data
+
+  //log the amount of time since the arduino has started, no necessary but migt be helpful
+  uint32_t m = millis();
+  logfile.print(m); //log milliseconds since start
+  logfile.print(", ");
+#if display_serial
+  Serial.print(m);
+  Serial.print(", ");
+#endif
+
+  //check the time
+  now = RTC.now();
+  //log time
+  logfile.print(now.get());
+  logfile.print(", ");
+  logfile.print(now.year(), DEC);
+  logfile.print("/");
+  logfile.print(now.month(), DEC);
+  logfile.print("/");
+  logfile.print(now.day(), DEC);
+  logfile.print(" ");
+  logfile.print(now.hour(), DEC);
+  logfile.print(":");
+  logfile.print(now.minute(), DEC);
+  logfile.print(":");
+  logfile.print(now.second(), DEC);
+#if display_serial
+  Serial.print(now.get());
+  Serial.print(", ");
+  Serial.print(now.year(), DEC);
+  Serial.print("/");
+  Serial.print(now.month(), DEC);
+  Serial.print("/");
+  Serial.print(now.day(), DEC);
+  Serial.print(" ");
+  Serial.print(now.hour(), DEC);
+  Serial.print(":");
+  Serial.print(now.minute(), DEC);
+  Serial.print(":");
+  Serial.print(now.second(), DEC);
+#endif //display_serial
+
+//now log the sensor data
+//code for measuring voltage from https://create.arduino.cc/projecthub/next-tech-lab/voltmeter-using-arduino-00e7d1
+int voltage_value = analogRead(v_in_pin);
+  v_out = (voltage_value * 5.11) / 1024.00; //formula for calculating voltage out (V+) referece is 5.11v
+  float v_in = v_out / (R2/(R1+R2)); // to calculate voltage_in using voltage devider 
+  //float I = v_in / (R1+R2)
+
+  logfile.print(", "); 
+  logfile.print(v_in);
+  //logfile.print(", ")
+  //logfile.print(I)
+
+#if display_serial
+  Serial.print(", "); 
+  Serial.print(Vin);
+  //Serial.print(", ")
+  //Serial.print(I)
+#endif 
+
+   
+  digitalWrite(greenLED, LOW)
+}