$15 Datalogger using Arduino Micro-controller

Enclosed: All the Arduino datalogger code

Parts Required:

• Arduino UNO,
• SD Memory Shield
• Video Tutorial uses a more expensive version, the alternate selected has a different pin-out sequence
• Datasheet
  
• Micro-SD Flash,
• 9v Battery & connectors,
• USB programming cable,
• Arduino Proto Shield,
• & whatever sensors/actuators selected
• Book:  "Make: Sensors: A Hands-On Primer for Monitoring the Real World with Arduino and Raspberry Pi" 
• http://www.amazon.com/Make-Sensors-Hands-On-Monitoring-Raspberry/dp/1449368107 

Note:  If your Arduino Uno datalogger works fine on USB power, but fails when on battery or external power, change the value of R12 from 1k to 10k.  A known feedback condition may be corrupting the initialization process.  Schematic

Also enclosed below are video tutorials that allow for understanding the code to create a datalogger.  Many micro-SD card shields exist for as little as about $1.50 (USD).  The tutorial uses a different version than the one used by us.  SD card shields (circuit boards) and SD memory cards.

As instructors, you can choose whether to teach coding, just assemble the datalogger, or some combination.

Recommendation if teaching coding: teach how to set up small amounts of code and check usefulness, save incremental versions, and add tested code in pieces.  Back up incremental accomplishments.  That way one problem is being solved at a time, and not working on 10 simultaneous problems; usually syntax errors.

Use // to comment out code that is working, to debug code

When starting from scratch, the four layers of coding:

1. Details, objectives, correlations, description of sequences, anticipated restrictions, and risks all written in English;
   
2. Flow Chart and/or State Diagram to reflect written English;
3. Pseudo-code (ends up driving code comments); &
4. Syntax Correct code
   
   followed by:
   entering code
   testing, and
   debugging

All tutorials are added for completeness.  But the main ones for the datalogger are: start with 11, then 1, 3, 6, 7, 8, & repeat 11

In one class period (or homework assignment) the students can read through everything needed to make a datalogger.  With 10% expected uptake.  Hands-on practiced experience is needed to correlate the conveyed information effectively.

An important aspect is to as much as practical, have the students learn "how" to solve their own problems.  The act of getting practices experience in problem solving better prepares them for actual life experiences.

The students can then at your option write and implement code based upon tutorials, or just build the datalogger and explore other class efforts.

For explanations:
SD.h library reference http://arduino.cc/en/Reference/SD
Wire.h library reference http://arduino.cc/en/Reference/wire

Tutorials at times use a software called "Processing".  The more advanced code editor for Arduino; free from

     https://www.processing.org/download/
     select "no donation" to download

"Processing" code (Arduino code is based on Processing code) uses .pde file extensions and contains the code in text format.

Each of the Video tutorials has a related download page for the related code, to minimize making typos.

"Arduino" automatically includes libraries, while "Processing" requires "Import" of every library used.
 

Arduino Free Software Downloads: www.Arduino.cc ; all parts can be purchased on eBay (~$15 total)

Tutorial 01 for Arduino: Getting Acquainted with Arduino

http://www.youtube.com/watch?v=fCxzA9_kg6s

Tutorial 02 for Arduino: Buttons, PWM, and Functions

http://www.youtube.com/watch?v=_LCCGFSMOr4

Tutorial 03 for Arduino: Electrical Engineering Basics

http://www.youtube.com/watch?v=abWCy_aOSwY

Tutorial 04 for Arduino: Analog Inputs

http://www.youtube.com/watch?v=js4TK0U848I

Tutorial 05 for Arduino: Motors and Transistors

http://www.youtube.com/watch?v=5bHPKU4ybHY

Tutorial 06 for Arduino: Serial Communication and Processing

http://www.youtube.com/watch?v=g0pSfyXOXj8

Tutorial 07 for Arduino: I2C Communication and Processing

http://www.youtube.com/watch?v=GJX0BRUagCg

Tutorial 08 for Arduino: SPI Interfaces

http://www.youtube.com/watch?v=1nO2SSExEnQ

Tutorial 09 for Arduino: Wireless Communication

http://www.youtube.com/watch?v=vKVNmA8C6m8

Tutorial 10 for Arduino: Interrupts and Hardware Debouncing

http://www.youtube.com/watch?v=CRJUdf5TTQQ

Tutorial 11 for Arduino: SD Cards and Datalogging

http://www.youtube.com/watch?v=5v5A3j7Rrco

Tutorial 12 for Arduino: RFID Card Reading

http://www.youtube.com/watch?v=gIlSLwcbeTU

Tutorial 13 for Arduino: Liquid Crystal Displays (LCDs)

http://www.youtube.com/watch?v=oIiDseJO4dM

Tutorial 14 for Arduino: Holiday Lights and Sounds Spectacular!

http://www.youtube.com/watch?v=CoG_Czyr7z0

Tutorial 15 for Arduino: GPS Tracking

http://www.youtube.com/watch?v=TtZEZYQG0xk

Actual Code to Use with specified Catalex SD Card Adapter

Arduino to SD Card Adapter wiring connections

//Program by Jeremy Blum
//www.jeremyblum.com
//SD Card Demonstration
//Some code from public domain work by Tom Igoe
//Some code modified by James Dunn

#include <SD.h>         //SD Card Library
#include <Wire.h>       //I2C Library

//SPI SD Card Pins
  //MOSI = Pin 11
  //MISO = Pin 12
  //SCLK = PIN 13
  int CS_pin = 10;
  int pow_pin = 8;
 
//I2C Temperature Pins
  //SDA = Analog Pin 4
  //SCL = Analog Pin 5
 
//IR Distance Sensor Pins
  int IR1_pin = 2;
  int IR2_pin = 3;
 
//Light Sensor Pins
  int light_pin = 1;

float refresh_rate = 0.0;  //Dataloger Refresh Rate
int temp_address = 72;     //Address of the I2C Temp Sensor
long id = 1;                //Use this to store the id # of our reading.

void setup()
{
  Wire.begin();
  Serial.begin(9600);
  Serial.println("serial set at 9600 baud");

  //CS Pin is an output
  pinMode(CS_pin, OUTPUT);
  Serial.println("CS_pin set as OUTPUT");
 
  //SD Card will Draw Power from Pin 8, so set it high
  pinMode(pow_pin, OUTPUT);  
  digitalWrite(pow_pin, HIGH);
  Serial.println("pow-pin 8 set as OUTPUT and HIGH");
 
  //Initialize SD Card with CS_pin = 10
  if (!SD.begin(CS_pin))
  {
      Serial.println("Card Failure - CS_pin 10 no signal");
      return;
  }
  Serial.println("Card Ready - Signal on CS_pin 10");
 
  //Create configuration file COMMANDS.txt
  File commandFile = SD.open("COMMANDS.txt", FILE_WRITE);
  commandFile.write(1000);
  commandFile.close();
 
  //Read the Configuration information (COMMANDS.txt)
  commandFile = SD.open("COMMANDS.txt", FILE_READ);
  if (commandFile)
  {
    Serial.println("Read from COMMANDS File");
    
    float decade = pow(10, (commandFile.available() - 1));
    while(commandFile.available())
    {
      float temp = (commandFile.read() - '0');
      refresh_rate = temp*decade+refresh_rate;
      decade = decade/10;
    }
    Serial.print("Refresh Rate = ");
    Serial.print(refresh_rate);
    Serial.println("ms");
 
  }
  else
  {
    Serial.println("Could not read command file.");
    return;
  }
  commandFile.close();
  Serial.println("close command file");
 
  //Write Log File Header
  File logFile = SD.open("LOG.csv", FILE_WRITE);
  Serial.println("opened LOG.csv file");
 
  if (logFile)
  {
    logFile.println(", , , ,"); //Just a leading blank line, in-case there is previous data
    String header = "ID, Light, Temp, IR1, IR2";
    logFile.println(header);
    Serial.println("wrote this header to LOG.csv: ");

    Serial.println(header);
  }
  else
  {
    Serial.println("Couldn't open LOG.csv file");
  }
 
}

void loop()
{
  //Check Light Level
  int light_level = analogRead(light_pin);
 
 /* uncomment this section if using related temperature IC chips
  //Read Temperature
  Wire.beginTransmission(temp_address); //Start talking
  Wire.write(0);//Ask for Register zero
  Wire.endTransmission(); //Complete Transmission
  Wire.requestFrom(temp_address, 1); //Request 1 Byte
  while(Wire.available() == 0); //wait for response
  int temp_c = Wire.read(); // Get the temp
  int temp_f = round(temp_c*9.0/5.0 +32.0);  //Convert from Celcius to Fahrenheit
  */
    int temp_f = round(32.0); // delete this line if using related temperature IC chips
 
  //Read Distances
  int IR1_val = analogRead(IR1_pin);
  int IR2_val = analogRead(IR2_pin);
 
  //Create Data string for storing to SD card
  //using CSV Format  
  String dataString = String(id) + ", " + String(light_level) + ", " + String(temp_f) + ", " + String(IR1_val) + ", " + String(IR2_val);
 
  //Open a file to write to
  //Only one file can be open at a time
  File logFile = SD.open("LOG.csv", FILE_WRITE);
  if (logFile)
  {
    logFile.println(dataString);

    Serial.println(dataString);
  }
  else
  {
    Serial.println("Couldn't open log file");
  }
  logFile.close();
 
  //Increment ID number
  id++;
 
  delay(refresh_rate);
 
}