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Mini-Z Track TimerX

Posted March 5, 2012 by Chris

“The circuit is based around the Atmel AT90S8515. All but 1 of the I/O pins have been used: 15 for the display multiplexing, 1 for the buzzer, 3 for the input switches, 4 for the track lap sensors, 5 for the gantry lights (4 are dedicated to the ISP programming). There are a total of 32 display digits, each made of 7 segments and 1 decimal place. Hence there are 8×32, or 256 LEDs to control. The multiplexing is done by using 5 I/O pins to select the digit, and 8 I/O pins to select the segments”

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