My Arduino Projects
-------------------

This is my collection of small projects I've done on the Arduino platform.

1. datalog - a small stand-alone data logger capturing temperature on SD card

1. datalog
==========

1.1 Hardware
------------

  * Arduino Uno
  * Adafruit Data Logger Shield [1]
  * 1 Push Button
  * 1 DS 18S20 Temperature Sensor
  
  Wiring:
  
  DIGITAL 2    Input Push Button (Toggle log recording on SD card)
  DIGITAL 3    red LED (on = log is written to SD)
  DIGITAL 4    green LED (on = operational)
  DIGITAL 7    data pin DS 18S20

  * See [2] on how to connect a button 
  * The two LEDs are already available on the shield 
    You only have to connect them to the DIGITAL ports of the Arduino
  * The temperature sensor needs +5V and GND addtionally.
    Take these lines directly from the shield
    See [3] for the pin out of the sensor
    I put the 3 sensor lines on a connector so you can attach a wire
    and place the sensor freely detached from the board.

  [1] http://www.ladyada.net/make/logshield/
  [2] http://www.arduino.cc/en/Tutorial/button
  [3] http://datasheets.maximintegrated.com/en/ds/DS18S20.pdf

1.2 Firmware
------------

  Build

  * Install the RTClib from Arduino's site [1]
  * Install the OneWire library [2]
  * Compile and run the Arduino datalog.ino sketch found here in the
    Arduino IDE
  
  [1] http://www.ladyada.net/make/logshield/rtc.html
  [2] http://www.arduino.cc/playground/Learning/OneWire

  Startup
  
  * Insert a SD Card and make sure the clock battery is inserted
  * Reset or power on Arduino
  * Open the serial console in the Arduino IDE to see the output of the logger
  
  LED Output

  * The green light should be enabled and it blinks every time the
    temperature is measured
  * If the red LED blinks then something went wrong
    * Check SD Card
    * Check temperature sensor
    * Check Real Time Clock
    * Reset and try again
    * See serial console for error message
  * If the red LED stay on then logging to a file on SD card is enabled
  
  BUTTON Input
  
  * If you press the button for the first time then the logger starts to
    write the temperature values to a log file on the SD card. The red
    LED is enabled.
  * If you press the button again then the logger stops writing to SD card
    and closes this file. The red LED is disabled.
    
  SERIAL Output
  
  * First message is the detected temperature sensor type and the unique
    code of the sensor
  * Then in regular interval the temperature is measured and printed 
  * If some error occurrs it will be written to serial output, too
  
  SERIAL Input
  
  * You can input a line of text followed by a newline or return to enter
    commands (In Arduino IDE enable "Line Endings" in Monitor window!)
  * The following commands are recognized:
  
    'y' <nnnn>     - enter date year
    'm' <nn>       - enter date month
    'd' <nn>       - enter date day
    'H' <nn>       - enter time hours
    'M' <nn>       - enter time minutes
    'S' <nn>       - enter time seconds
    'a'            - adjust clock and write previously set values
    'r'            - read current clock values to allow adjustment
    'd' <nnnn>     - set the delay of temperature measurements in seconds
                     (default: 10)
    'o'            - open a log file on SD card
    'c'            - close the log file on SD card
  
  Initial Setup
  
  Its advisable to first setup the real time clock on your logger:
  In the serial console give the following commands (e.g. for today):
  
    y2012
    m10
    d20
    H11
    M25
    S00
    a
   
  As the clock is powered by the attached battery you can now disconnect
  the logger from your Host Mac/PC and use it standalone. Power it with a
  battery pack if you need it really portable.
    
  LOG FILES
  
  The log files are stored on SD card and are named automatically with the
  current date:
  
  <YY><MM><DD>_a.log
  
  The letter in the name is incremented automatically if a new log is written
  on the same day.
  
  A log contains lines that look like this:
  
  2012.10.19 22:04:56 +025.56 5081CE88 019C
  
  The columns denote the following:
    * date
    * time
    * temperature in degrees celcius
    * time stamp in UNIX format and hex
    * raw sensor value in hex (divide by 16 to get celcius value)