This week's assignment is to create a clock using Arduino. I created a clock that contains 10 LED lights, each light up for 6 seconds within 1 minute.
I started by drawing the clock shape and its circuit diagram. I decided to arrange 10 LEDs in a spiral shape, and the light would move toward the center of the spiral every 6 seconds for a minute. The sketch below shows the sequence in which the LEDs light up over a minute.
This design can be represented by the circuit diagram below. Each resistor-LED pair would be connected to a unique Arduino pin in order to control each LED separately.
The logic of this clock is simple. Since I separate 1 minute into 10 time intervals, I need 10 output ports to control the 10 LEDs. Therefore, in void setup(), I initialized the number 2 to 11 pins. Then, in void loop(), I wrote second = int((floor(millis()/1000))) % 60 to convert the number of milliseconds into the number of seconds within the range of [0,59]. Initially, I wrote second = (floor(millis()/1000)) % 60 but received an error. Upon searching online, I learned that this is because floor(millis()/1000) gives a double type number, while % (modulo) only works for integer type. Therefore, I use the int() function to convert the current number of seconds into an integer.
Configuring the breadboard was harder than expected. While the circuit diagram seems straightforward, I had to consider where to put each component and wire so that the circuit works as expected and the LEDs form a spiral. Below are the steps I took to configure the breadboard:
- I first adjusted the positions of the Arduino board and the LED lights. Initially, I wanted to move the LED spiral away from the board. However, that required more wires and longer wires, which can make my breadboard very messy. Therefore, I put the LEDs as close to the Arduino board as possible.
- Then, I put the resistors on the breadboard. Since each LED and its resistor are connected in series, resistors can be directly connected to the ground so I can use fewer wires.
- I connected the Arduino ground pin with a long column labeled "-" on one side of the breadboard using a short black wire. Then, I used a long black wire to connect the two "-" columns on both sides of the breadboard so that the two columns are both connected to the ground. This enables LEDs and resistors to connect neatly on the breadboard.
Speed x2, side view only:
Speed x5, side view only:
Normal speed, side view and top view:
