Since any PORT P1 pin is able to source a max. of 20mA per pin with
P1 capable of sourcing a total maximum current of 80mA, hence we
can use P1 to drive LED display directly. As shown in the circuit, 8
LEDs are connected to P1 with each 120 Ohm current limiting
resistors.
1) For SPJ 8051 C, the following code,
led_spj.c
2) For KEIL 8051 C, the following code,
led_89.c
demonstrate how to output and turn on & off the LEDs. The program
blinks LED from LED1 to LED8 turning on & off one after another
sequentially. When it reaches LED8, it repeats all over again.
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EXERCISES
Modify the above program to display
the following sequence : -
LED1 and LED8 turn on, 1 sec delay;
LED2 and LED7 turn on, 1 sec delay;
LED3 and LED6 turn on, 1 sec delay;
LED4 and LED5 turn on, 1 sec delay;
Loop back & Repeat again forever.
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