Hola a todos, queria ver si pueden ayudar a corregir un programa de un ADC0831 con el 16f84, el problema es que no me detecta el ADC. O si tienen uno que controle los pulsos de un led con un potenciometro. Este es el codigo:
;=======ADC831.ASM============================Rex N. Fisher===4/15/98=====
;Adaptation of a program originally published as an application note by
;Parallax, Inc.
;This program demonstrates the use of an external serial ADC (National
;ADC0831) with the PIC16C84 microcontroller. A variable voltage (0-5V) at
;pin 2 of the ADC controls the blinking rate of an LED connected to pin 2
;of the PIC.
;Hardware connections:
;
; *Pin 1 (RA2) to pin 1 of ADC
; *Pin 2 (RA3) to 470 ohm (470 to diode anode, diode cathode to GND)
; *Pin 3 (RTCC) to +5V
; *Pin 4 (_MCLR) to +5V
; *Pin 5 (Vss) to GND
; *Pin 6 (RB0) n/c
; *Pin 7 (RB1) n/c
; *Pin 8 (RB2) n/c
; *Pin 9 (RB3) n/c
; *Pin 10 (RB4) n/c
; *Pin 11 (RB5) n/c
; *Pin 12 (RB6) n/c
; *Pin 13 (RB7) n/c
; *Pin 14 (Vdd) to +5V
; *Pin 15 (OSC2) to pin 3 of ceramic resonator
; *Pin 16 (OSC1) to pin 1 of resonator (pin 2 of resonator to GND)
; *Pin 17 (RA0) to pin 7 of ADC
; *Pin 18 (RA1) to pin 6 of ADC
;
; Notes: Pin 2 of ADC is 0 - 5V input.
; Pin 3 & pin 4 of ADC to GND.
; Pin 5 & pin 8 of ADC to +5V.
;Theory of operation
;
; One or more external analog-to-digital converters (ADC) can be
; connected to the PIC16C84. A single ADC0831 is used here.
;
; Interafacing the ADC831 requires only three I/O lines, and of these,
; two can be multiplexed with other functions (or additional ADC831s).
; Only the chip-select (CS) pin requires a dedicated line. The
; ADC"s range of input voltages is controlled by Vref and Vin(-) pins.
; Vref sets the voltage at whivh the ADC will return a full-scale
; output of 255 (Ffh), while Vin(-) sets the voltage that will
; return 0.
;
; In this example, Vin(-) is at ground and Vref is at +5V; however
; these values can be as close together as 1 volt without harming
; accuracy or linearity. Diode voltage references or trim pots may
; be used to set these values.
;
; This program reads the voltage at the ADC831"s input pin and uses
; the 8-bit result to control a timing routine that flashes an LED.
; The LED flashes slowly when the input is +5V, and very rapidly as
; it approaches ground.
;
; The subroutine "Convert" handles the details of getting data out of the
; ADC. It enables the ADC by pulling the CS line low, then pulses the
; clock line (CLK) to signal the beginning of a conversion. The program
; then enters a loop in which it pulses CLK, gets the bit on pin DAT,
; and shifts it into the received byte using the rotate left (rlf)
; instruction. Remember that rlf shifts the carry bit into the LSB of
; the specified register (and the MSB back into the carry bit).
;
; When all bits have been shifted into the byte, the program turns off
; the ADC by returning CS high. The subroutine returns with the
; conversion result in the variable AD_RSLT. The value of AD_RSLT is
; moved to COUNT1 and determines the length of the delay loop (blink
; rate).
;Possible modifications:
;
; More ADC831"s can be added to the circuit. Connect each additional
; ADC to the same clock and data lines, but assign separate CS pins.
; Modify the "Convert" subroutine to take the appropriate CS pin low
; when it needs to acquire data from a particular ADC.
;=======Programming Instructions===========================================
;Select the following settings at time of programming:
; Device = 84
; Oscillator = XT
; Watchdog = OFF
; Timer = ON
; Code Protect = OFF
;=======Program Hierarchy================================================
; Main
; Initialize
; Blink
; Wait
; Convert
;=======Header Section===================================================
;Select PIC16C84 processor and default radix.
LIST p=16F8A4 ;Assemble for specific features of PIC16F84.
radix HEX ;Default number system is hexadecimal.
;P16C84.INC defines configurations, registers, and other useful bits of
;information for the PIC16F84 microcontroller. The names assigned to registers
;and pins match the Microchip data sheets as closely as possible.
include <P16F84A.INC>
;=======Equate Section===================================================
;Register equates:
SRAM equ 0C ;RAM locations (GP registers) start at 0Ch.
RA equ 05 ;RA is another name for PORTA.
RB equ 06 ;RB is another name for PORTB.
;Bit equates:
CLK equ 0 ;Bit 0 of RA (ADC clock).
DAT equ 1 ;Bit 1 of RA (ADC data).
CS equ 2 ;Bit 2 of RA (ADC chip select).
LED equ 3 ;Bit 3 of RA (LED).
;=======Variable Section==================================================
cblock SRAM ;Assign variable names to data memory locations.
;starting at the address defined by SRAM.
COUNT0 ;Counter for delay loop.
COUNT1 ;Counter for delay loop.
COUNT2 ;Counter used to read 8 data bits from ADC.
AD_RSLT ;Result of A/D conversion.
Endc ;End of data memory assignments.
;=======Vector Section===================================================
org 00 ;Program memory locations start at 00h.
;Reset vector is 00h. Start here after reset.
goto Main ;Branch to program (starting at Main).
org 05 ;Interrupt vector is 04h.
Int ;Start here after interrupt.
goto Int ;Endless loop (stops program on interrupt).
;=======Table Section====================================================
;No tables for this program.
;=======Program Section==================================================
Main ;Start program here.
call Initialize ;Initialize variables and registers.
Blink ;Toggle the LED on and off.
movlw B"00001000" ;Create bit mask for bit 3 (RA.3 = LED).
xorwf RA,F ;Invert output bit to LED.
call Wait ;Variable delay depending on ADC data.
goto Blink ;Go toggle the LED again.
;-----------Initialize Subroutine-------------------------------------------------------------------------------
;
;Zero variables and configure I/O pins.
Initialize
;Clear variables.
clrf COUNT0
clrf COUNT1
clrf COUNT2
clrf AD_RSLT
;Clear RA and RB before setting direction.
clrf RA
clrf RB
;Set direction register for RA and RB.
bsf STATUS,RP0 ;Access bank 1 of register files.
movlw B"00000010" ;Make bit 1 an input, others are outputs.
movwf TRISA ;Program I/O bits of RA.
movlw B"00000000" ;Make all bits outputs.
movwf TRISB ;Program I/O bits of RB.
bcf STATUS,RP0 ;Return to bank 0 of register file.
return
;-----------Wait Subroutine-----------------------------------------------------------------------------------
;
;Determine the blinking speed of the LED, which depends on the data received
;from the ADC. If the input voltage to the ADC is high (close to +5V), the
;8-bit data value is large and the blink rate is slow. The blink rate becomes
;faster as the input voltage to the ADC is reduced, and the 8-bit data value
;becomes smaller.
Wait
call Convert ;Get result of A/D conversion & put in AD_RSLT.
;Put data from ADC (AD_RSLT) into COUNT1.
movf AD_RSLT,W
movwf COUNT1
;Add 1 to COUNT1 to prevent underflow when AD_RSLT = 0.
movlw 01
addwf COUNT1,F
Delay ;Produce a time dleay that depends on the data
;from the ADC, which was previously put into
;COUNT1
;The delay determined by COUNT0 is fixed at 0FFh (256d) loops.
decfsz COUNT0,F ;Decrement COUNT0. Decrement COUNT0 again if
goto Delay ;COUNT0 is not equal to 0. Fall through if
;COUNT0 is equal to 0.
;The delay determined by COUNT1 is dependent upon the A/D conversion
;result, which was put into COUNT1.
decfsz COUNT1, F ;Decrement COUNT1. Go back and decrement
goto Delay ;COUNT0again if COUNT1 is not equal to 0.
;Fall through if COUNT is equal to 0.
return
;-----------Convert Subroutine-------------------------------------------------------------------------------
;
;Enable the ADC, signal the ADC to begin a data conversion, read the ADC data
;one bit at a time, put the 8-bit data value into AD_RSLT, disable the ADC.
Convert
bcf RA,CS ;Clear pin 2 of RA (CS) to enable ADC.
;Set up COUNT2 for eight data bits from ADC to be moved into AD_RSLT.
movlw 08
movwf COUNT2
;Pulse CLK pin of ADC to signal the beginning of a conversion.
bsf RA,CLK ;Set CLK to 1.
nop ;Hold 1 on CLK (necessary if PIC clock >4MHz).
bcf RA,CLK ;Reset CLK to 0.
clrf AD_RSLT ;Clear register before reading new ADC data.
Read_Bit ;Pulse CLK to read data bit from ADC,
;read the data bit, and shift it into AD_RSLT
;Repeat 8 times to read the entire data byte.
bsf RA,CLK ;Set CLK to 1.
nop ;Hold 1 on CLK (necessary if PIC clock >4MHz).
bcf RA,CLK ;Reset CLK to 0.
;Read data bit from ADC and set carry bit equal to the data bit.
btfss RA,DAT ;Is data bit equal to 1?
bcf STATUS,C ;Clear carry bit equal to 0?
btfsc RA,DAT ;Is data bit equal to 0?
bsf STATUS,C ;Set carry bit if data bit is not equal to 0.
;Put data bit into AD_RSLT and go get next data bit.
rlf AD_RSLT,F ;Shift carry bit (equal to ADC data bit)
;into AD_RSLT.
decfsz COUNT2,F ;Decrement COUNT2.
goto Read_Bit ;Read 8 bits (until COUNT2 = 0).
;Fall through loop after all 8 bits are read.
bsf RA,CS ;Set pin 2 of RA (CS) to disable ADC.
return
end ;End of program.
;=====================================================================
Gracias por su ayuda.
