Commit e9914239 authored by Arlo's avatar Arlo
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the voltmeter code combined with write to SD code. In order to measure voltage...

the voltmeter code combined with write to SD code. In order to measure voltage and log it to an SD card
parent ce315695
#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: ");
digitalWrite(redLED, HIGH); //turn on red led to signal error
while(1); // halt, sits in it forever until restarted
void setup(void)
#if start_command
Serial.println("type any character to start")
while (!Serial.available());
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 =, 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: ");
//now use the wire library to start the Real Time Clock
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
#if display_serial
#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(", ");
//check the time
now =;
//log time
logfile.print(", ");
logfile.print(now.year(), DEC);
logfile.print(now.month(), DEC);
logfile.print(, DEC);
logfile.print(" ");
logfile.print(now.hour(), DEC);
logfile.print(now.minute(), DEC);
logfile.print(now.second(), DEC);
#if display_serial
Serial.print(", ");
Serial.print(now.year(), DEC);
Serial.print(now.month(), DEC);
Serial.print(, DEC);
Serial.print(" ");
Serial.print(now.hour(), DEC);
Serial.print(now.minute(), DEC);
Serial.print(now.second(), DEC);
#endif //display_serial
//now log the sensor data
//code for measuring voltage from
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(", ")
#if display_serial
Serial.print(", ");
//Serial.print(", ")
digitalWrite(greenLED, LOW)
\ No newline at end of file
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