8 LED Effects using PIC16F84A

Posted on Aug 7, 2012

Five pins RA0 to RA4 are used as inputs. The pins are connected to the 5V average resistance 10K (Pull-up). So when no switch is not depressed all the pins have a high potential (HI +5 V). When one of them is pressed then the foot is connected to get a low potential (LOW 0V). When a switch is pressed, then the phenomenon of 'Bounce' (Debaunce), this is because the switch does not always close the circuit but once more (rebounds) leading the microprocessor takes several input signals. In our example code is not used to prevent rebound as soon as one pressed the switch immediately begins the routine imaging of the selected effect which is greater than this year's rebound.

8 LED Effects using PIC16F84A
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Circuit output (Driving Led) Eight feet by RV7 RV0 used as outputs - drivers Led. Among them inserted 560R resistors, which limit the current flowing through the output pins and protect them from destruction. The descent of the led associated with resistance and rise to 5V. When the output is in a foot (HI +5 V) the led is not lit and when it is (LOW 0V) glows. In this example we used high brightness led to reduce the current flowing through each leg. Timing Circuit For the timing of the processor used a ceramic filter (Resonator) or 10MHz crystal and two 22pF ceramic capacitors Feeder circuit The IC2 stabilize the voltage from 12VDC to 5VDC and capacitors to smooth and filter. Since the consumption of the circuit is too low a stabilizer of about 100mA is enough.

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