Prototype Display

I built a quick prototype display unit. The microcontroller is a PIC18F4550 chip. The T1OSO pin 17 receives the pulse signal from the RPM sensor. The chip's program reads this value three times a second. This value is converted into revolutions per minute and display on the 7 LEDs.

I was not sure how bright I wanted to make the LEDs. So, I decided to use the PWM feature of the PIC18F. The AN0 pin 2 reads a voltage value from a potentiometer. This value is used to scale the Pulse Width of the signal sent out Pin 17 CCP1. This signal drives a TIP120 NPN transistor to sink current from the LEDs.