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Simulator Error On Pic16f877

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I wrote this program for PIC16F877



void main(void)


trisa = 0xff;

trisb = 0;




if ((porta & 010b) == 010b)


portb = 0xff;




portb = 0;





Under simulator I assigned button to porta Pin 1 and LED block to portb and result was - portb doesn't set at all when I push button.


This code works for PIC16F84.

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This is one of the classic mistakes ;)


The PIC16F877 also uses PORTA pins for analog inputs.

The default port mode is analog input.

Just changing the tris register for PORTA doesn't turn off the analog mode.


Please the data sheet, you need to also change ADCON registers to turn off the analog mode.




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