Scalextric Lap Counter

Posted on Feb 5, 2014

After getting some Micro Scalextric for Christmas and shortly after acquiring a vast mount of second-hand track from eBay I decided I needed a lap counter so I could race against the clock with opponents. I didn`t just want to see who could do 10 laps first I wanted to time the laps to a reasonable degree of accuracy to see who was fastest. Bu

Scalextric Lap Counter
Click here to download the full size of the above Circuit.

ilding something to do that shouldn`t be too difficult I thought, and now here is my project page for my Scalextric Lap Counter. The lap counter is based around a PIC Microprocessor, a couple of IR LEDs and IR Photodiodes, and an LCD character display. The basic theory of operation is that the PIC will be running a timer and each time the IR light beam is broken by a car crossing the finish line the lap time will be recorded and displayed in the LCD. The circuit for the lap counter is actually fairly simple. There are 2 IR LEDs (one for each track) that are constantly powered and 2 IR Photodiodes to detect the light. When the IR light is detected (beam not broken) the voltage going to the input pin on the PIC is 5v. When the beam is broken the voltage drops to 0v (or thereabouts). I`ve also added a couple of push buttons to let the user reset the individual lap times and counter for each track. The last bit of the circuit is the LCD display which uses up all the spare pins on the PIC! The LCD display I chose to use is a 16G—2 character display. These displays have a number of control lines and eight data lines in order to display text on the screen. Once the display is initialised sending text to the the screen is pretty straight forward. You simply set the R/S line high  as you`re sending text, set the R/W line low  as you`re writing to the display, and set the Enable line high . You then send the ASCII code for the...

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