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This is an easy project to assemble- just one main board and two shields, but gives a fully functional, easy to read clock display which retains the time, even when disconnected from power. You could leave it on your desk plugged into a USB port on your computer, so that it powers up whenever the computer is on.
All the connections are made with interconnects on the shield, but the following are the important pins:
|D10||SD Card Select|
|D11||Master In Slave Out|
|D12||Master Out Slave In|
|D4||LCD Data bit0 (in 4bit mode)|
|D5||LCD Data bit1 (in 4bit mode)|
|D6||LCD Data bit2 (in 4bit mode)|
|D7||LCD Data bit3 (in 4bit mode)|
|D8||LCD Register select|
Stack the shields, first the Data Log Shield onto the Uno, then the LCD Shield onto the Data Log Shield. Make sure you’ve got the RTClib Library installed. The project also uses the Wire and LCD libraries, but they are included with the Arduino IDE.
Compile and upload the code to the board, and the clock should display a time and date (which probably isn’t right). The clock can be adjusted by pressing select, then left and right to choose which field to edit, and up and down to adjust the field. The seconds can only be set to zero rather than adjusted up or down. Press select again to return to clock mode.
With the addition of a buzzer module, the code could be modified to act as an alarm clock. Once the clock is set, the sketch on the main board can be changed, so the buttons could be reprogrammed to operate different functions, such as a countdown timer.