This project uses a waterproof ds18b20 sensor to log pool water temperature to an SD card and displays the temperature on an LCD.
For this project, an Arduino Uno was used to create a waterproof water temperature logger. The project used an Arduino data logger shield and an LCD keypad shield to achieve a simple modular design. The device logs to the SD card every 30 seconds and displays the time, number of data points, battery voltage and temperature on the LCD.
To create this project the following components were used:
How I built this project:
Data logging shield
The data logging shield includes an sd card slot, a DS1307 Real Time Clock with battery backup and prototype space. The prototype space was used to connect the DS18B20 and the battery monitoring voltage divider. The "Batt" connection on the circuit diagram was connected via a wire under the board to the positive of the DC jack on the Arduino Uno.
LCD Keypad
The DFR0009 DFRobot LCD keypad shield uses pin10 for backlight control, however, pin 10 is already being used by the data logging shield for the SD chip select. The header for pin10 was removed and a piece of wire used to bridge a connection to pin4 so pin4 can now be substituted to control the LCD backlight.
Software and putting it all together
The Arduino was programmed using the Arduino IDE. Code for the project is linked below. The code makes use of open source libraries available in the Arduino IDE, and I would like to thank the various library authors for their contributions.
After going through some initialisation routines to check the clock has a valid time (The DS1307 example in the IDE is used to set the initial time) and that an SD card was inserted, the program logs temperature, battery voltage and time to the SD card every 30 seconds. The data is also shown on the LCD. As there is no attempt to minimise power usage besides turning off the backlight between samples the device only runs for about 48 hours on 6xAA batteries. For the intended purpose, this was suitable and rechargeable batteries were used to provide a better solution. The final build was fitted into a waterproof project enclosure with clear lid to prevent damage from any splashing.
