The schematic above is basic circuitry used in the implementation on the sign. It is powered by the A3BU, goes through a 110 ohm resistor before continuing to the LEDs where it daisy chains to each LED in that particular circuit. As mentioned above, there are 7 different circuits on the sign. One circuit for each of the LED colors(5) and two for the red and white LEDs on the letters “U” and “L”. This was done because we wanted to display U L without the rest of the sign being lighted. Although this is very basic circuitry, there were 114 LEDs on the sign, therefor soldering all the connections was very time consuming. But, it went together very well and we had no bad LEDs or bad connections to redo. The 5V power was coming from the J1 header on the A3BU. We used 7 J1 header pins, one for each circuit, and then grounded all LEDs to the A3BU via one ground.
As we are learned the code in lab 4 for ADC and PWM signal. I change the internal temperature sensor to the internal light sensor to control the frequency of the PWM signal, “adcch_set_input(&adcch_conf, ADCCH_POS_PIN0, ADCCH_NEG_NONE, 1); “. For the night LED will flash cause it have low frequency. and for the day you can see the solid light as the high frequency. Then we are set the while loop to display the pattern we want. below is the code PWM signal send out from the 7 pin of A3BU. Each pin connect to 110 ohm resistor then connect to the LED circuit. Here is a link to the full code we are use for our project. (we modified the code from the ADC internal temperature of A3BU in new example) .
The final project that our group, DayStar, decided to work on is a LED sign that reads, “Welcome to U of L”. The implementation of a light sensor gives us the ability to change the frequency of the LED lights. With all the LEDs wired together, we are using the Atmel software with an A3BU board to control the abilities.