Write a code on the PIC microcontroller PIC16F877A

Imagine you are writing code to display a bar graph for the volume control of a stereo amplifier. Modify the code from assignment 14 to read voltage from POT0 instead of the count variable, and display the bar graph on the LED's.

;********************************************************************* ; This file is a basic code template for object module code * ; generation on the PIC16F877A. This file contains the * ; basic code building blocks to build upon. * ; * ; Refer to the MPASM User's Guide for additional information on * ; features of the assembler and linker (Document DS33014). * ; * ; Refer to the respective PIC data sheet for additional * ; information on the instruction set. * ; * ;********************************************************************** ; * ; Filename: MAIN.ASM * ; Date: * ; File Version: * ; * ; Author: * ; Company: * ; * ; * ;********************************************************************** ; * ; Files required: p16f877a.INC * ; 16f877a_g.lkr * ; * ; * ;********************************************************************** ; * ; Notes: * ; * ; * ; * ; * ;********************************************************************** LIST r=dec ; list directive to set the default radix list p=16F877A ; list directive to define processor #include "p16f877a.inc" ; processor specific variable definitions ; ; Defines and macros to help with ; bank selection ; Page 17 ; #define BANK0 (h'000') #define BANK1 (h'080') #define BANK2 (h'100') #define BANK3 (h'180') ; '__CONFIG' directive is used to embed configuration word within .asm file. ; The lables following the directive are located in the respective .inc file. ; See data sheet for additional information on configuration word settings. __CONFIG _CP_OFF & _CPD_OFF & _BODEN_OFF & _WDT_OFF & _PWRTE_ON & _HS_OSC & _LVP_OFF ;***** VARIABLE DEFINITIONS MAIN_DATA udata count res 1 delay_low res 1 delay_high res 1 ; example of using Shared Uninitialized Data Section INT_DATA UDATA_SHR w_temp RES 1 ; variable used for context saving status_temp RES 1 ; variable used for context saving pclath_temp RES 1 ; variable used for context saving ;********************************************************************** CODE org 0x000 ; processor reset vector RESET_VECTOR: nop ; ICD2 needs this goto start ; go to beginning of program INT_VECTOR: org 0x004 ; interrupt vector location INTERRUPT: movwf w_temp ; save off current W register contents movf STATUS,w ; move status register into W register movwf status_temp ; save off contents of STATUS register movf PCLATH,W movwf pclath_temp ; isr code can go here or be located as a call subroutine elsewhere movf pclath_temp,W movwf PCLATH movf status_temp,w ; retrieve copy of STATUS register movwf STATUS ; restore pre-isr STATUS register contents swapf w_temp,f swapf w_temp,w ; restore pre-isr W register contents retfie ; return from interrupt start: ; ; Turn off all analog inputs ; and make all pins available ; for digital I/O. ; banksel BANK1 movlw b'00000110' ; Set all ADC inputs for digital I/O movwf (ADCON1 ^ BANK1) ; movlw b'00000000' ; Turn off Comparator voltage reference movwf (CVRCON ^ BANK1) movlw 0x07 ; turn off Comparators movwf (CMCON ^ BANK1) banksel BANK0 clrf (ADCON0 ^ BANK0) ; Turn off ADC ; ; Set ports for digital output ; movlw b'00000000' movwf PORTA movlw b'00000000' movwf PORTB movlw b'00000000' movwf PORTC movlw b'00000000' movwf PORTD movlw b'00000000' movwf PORTE banksel BANK1 movlw b'00000000' movwf (TRISA ^ BANK1) movlw b'00000000' movwf (TRISB ^ BANK1) movlw b'00000000' movwf (TRISC ^ BANK1) movlw b'00000000' movwf (TRISD ^ BANK1) movlw b'00000000' movwf (TRISE ^ BANK1) banksel BANK0 clrf count clrf delay_low clrf delay_high

; remaining code goes here ; ; Make the LEDs on the LAB-X1 count ; main_loop: incf count,F movfw count movwf PORTD ; ; Pause between counts so humans ; can see the lights changing. ; delay_loop: incfsz delay_low goto delay_loop incfsz delay_high goto delay_loop goto main_loop END