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Unformatted text preview: display. After this, a digital dice that displays in random the number from 1 to 6 on the 7-segment LEDs is built. 3.
3.1. Experiment Equipments and Parts
LED Control Program PC, Breadboard, Power Supply, ROM Writer, PIC16F84, Crystal Oscillator (4MHz), Switch, LEDs, Resistors (330Ω, 10KΩ) 3.2. Digital Dice PC, Breadboard, Power Supply, ROM Writer, PIC16F84, Crystal Oscillator (4MHz), Switch, 7-segment LED, Resistors (330Ω, 2.2KΩ, 10KΩ) 4.
4.1.1 Theoretical Background
LED Control Program
Pull-up Resistor In this experiment, a pull-up resistor is used in the switch input circuit. Three types of the switch input circuit are presented from Figure 4.1.1 to Figure 4.1.3, for the purpose of showing why a pull-up resistor is necessary. First of all, suppose an input circuit as shown in Figure 4.1.1. This is an incomplete circuit because the state (‘high’ or ‘low’) of the device is not clearly determined when the switch is ‘open’, while its state is confirmed ‘low’ when the switch is ‘closed’. To...
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- Spring '10