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)