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Big MSP430 LED clock with brightness control

This would seem a regular LED clock. If not the fact that LED indicators are quite big. Indicator is 2” high and each segment is lit by 4 LEDs. So in order to light on LED bar the voltage drop is between 7.5 – 8.4V which is way bigger than microcontroller power voltage. So there is a special driving circuitry needed. To make it happen two special ICs are used – TLC59213 and TLC59310 that drives LED indicators at 10V. They have latches on inputs so they remain its state until next change.TLC59213 inputs are TTL and CMOS compatible so are easy to drive directly from microcontroller. The base of clock is MSP430F2101IDWR microcontroller which reads time data from MAX1337C RTC chip using I2C interface. For brightness control there is a dedicated ADC121C027 chip which reads photoresistor value which is used to control PWM waveform of LED indicator. Continue reading