[PIC] PIC16f887 delay 99ms

Jorge Hernández Garay · Nov 9, 2014

Hi guys! firstly thank you everyone for this excellent forum and for the help i'll receive even before i get it!

i'm a newbie in coding Assambly, i have a really terrible teacher and most of the time we students need to figure it out by ourselves.. not fair at all...

anyway... i need to create a code for counter delay of 99mS and i have no idea in how to start! i did before a simple one of 7ms but this new one use 16 bits and tmr1h tmr1l etc....

could you please guys give me a hand? what i've done was this:

Code ASM - [expand]
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;SET CONFIG REGISTER
 
        __CONFIG _CONFIG1,_LVP_OFF& _FCMEN_ON& _BOR_OFF& _CPD_OFF& _CP_OFF& _MCLRE_ON& _PWRTE_ON& _WDT_OFF& _INTRC_OSC_NOCLKOUT
 
        __CONFIG _CONFIG2,_WRT_OFF& _BOR21V
 
        ERRORLEVEL -302
 
;MACROS
BANK0   MACRO                                   ;SET UP MACRO TO SWITCH TO BANK 0
                        BCF STATUS, RP0
                        BCF STATUS, RP1
                        ENDM
 
BANK1   MACRO
                        BSF STATUS, RP0
                        BCF STATUS, RP1
                        ENDM
 
BANK3   MACRO
                        BSF STATUS, RP0
                        BSF STATUS, RP1
                        ENDM
 
;***************        VARIABLE DEFINITIONS    **************************************************************
COUNT1  EQU     0X20            ;USED FOR DELAY LOOP
COUNT2  EQU     0X21            ;USED FOR DELAY LOOP
;*********************************************************************************************************
;PROGRAM START
 
        ORG     0X000           ;PROCESSOR RESET VECTOR
        GOTO    MAIN    ;GO TO BEGINNING OF PROGRAM
MAIN    CALL SETUP
                CALL DELAY_TEST
 
                
 
 
 
                
 
;       GOTO REPEAT
 
;*********************************************************************************************************
;**************************     SETUP PROCEDURE **************************************************************
;       Initial settings for Pic Ports and Peripherals'
;*********************************************************************************************************
 
 
SETUP
        BANK0           ;SWITCH BANK TO BANK 0
        CLRF PORTA
        CLRF PORTB      ;SET UP INITIAL PORTB O/P CONDITIONS
        CLRF PORTC      
        CLRF PORTD
        CLRF PORTE
 
        BANK1                   ;SWITCH TO BANK1
 
        MOVLW 0XF0
        MOVLW TRISA             ;SET TRISA TO ALL O/Ps
        CLRF TRISC              
        CLRF TRISD
        BSF  TRISE, 0
        MOVLW 0X07
        MOVWF OPTION_REG
 
 
 
 
        BANK3
        CLRF ANSEL
        CLRF ANSELH
 
        BANK0                   ;SWITCH BACK TO BANK 0
        RETURN
 
;********************************************************************************************************
;*********************  DELAY FOR APPROX 22mS ***********************************************************
; MAXIMUM DELAY AVAILABLE APPROX 65mS (4MHz PROCESSOR)
;********************************************************************************************************
 
DELAY_TEST
        BCF INTCON, T0IF
        MOVLW 0XAA                      ;SET UP DELAY COUNTERS
        MOVWF TMR0
XX  BTFSS INTCON, T0IF
        GOTO XX
        
 
RETURN 
 
;********************************************************************************************************
 
        END

thank you in advance~~!!!!!!

milan.rajik · Nov 9, 2014

You have to use Timer1 Interrupt to produce 99 ms delay. The interrupt will occur every 99ms.

https://www.best-microcontroller-projects.com/article-pic-timer-calculation.html

https://forum.allaboutcircuits.com/threads/55-sec-time-delay-in-assembly-language.9993/

Timer0 example. Make a similar code for Timer1.

www.gooligum.com.au/tutorials/baseline/PIC_Base_A_5.pdf

Jorge Hernández Garay · Nov 9, 2014

thank you mate! but how do we determine the 16 bits for TMR1H AND TMR1L?

I'm using the formula: 65536- (99ms X (1Mhz/4) so my result is 16036 which in HEX is: 3EA4 then split in 2 :

TMR1H 3E
TMR1L A4

but still no working. this is what i've done:

Code ASM - [expand]
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;PROGRAM START
 
        ORG     0X000           ;PROCESSOR RESET VECTOR
        GOTO    MAIN    ;GO TO BEGINNING OF PROGRAM
MAIN    CALL SETUP
                CALL DELAY_TEST_2
 
                
 
 
 
                
 
;       GOTO REPEAT
 
;*********************************************************************************************************
;**************************     SETUP PROCEDURE **************************************************************
;       Initial settings for Pic Ports and Peripherals'
;*********************************************************************************************************
 
 
SETUP
        BANK0           ;SWITCH BANK TO BANK 0
        CLRF PORTA
        CLRF PORTB      ;SET UP INITIAL PORTB O/P CONDITIONS
        CLRF PORTC      
        CLRF PORTD
        CLRF PORTE
        BTFSS PIR1, TMR1IF
        MOVLW 0X31
        MOVWF T1CON
 
        BANK1                   ;SWITCH TO BANK1
 
        MOVLW 0XF0
        MOVLW TRISA             ;SET TRISA TO ALL O/Ps
        CLRF TRISC              
        CLRF TRISD
        CLRF  TRISE
;       MOVLW 0X07
;       MOVWF OPTION_REG
        BSF PIE1, TMR1IE
 
 
        BANK3
        CLRF ANSEL
        CLRF ANSELH
 
        BANK0                   ;SWITCH BACK TO BANK 0
        RETURN
 
;********************************************************************************************************
;*********************  DELAY FOR APPROX 22mS ***********************************************************
; MAXIMUM DELAY AVAILABLE APPROX 65mS (4MHz PROCESSOR)
;********************************************************************************************************
 
DELAY_TEST
        BCF INTCON, T0IF
        MOVLW 0XAA                      ;SET UP DELAY COUNTERS
        MOVWF TMR0
XX  BTFSS INTCON, T0IF
        GOTO XX
        
 
RETURN 
;********************************************************************************************************
;*********************  DELAY FOR APPROX 22mS ***********************************************************
; MAXIMUM DELAY AVAILABLE APPROX 65mS (4MHz PROCESSOR)
;********************************************************************************************************
 
DELAY_TEST_2
        BTFSS PIR1, TMR1IF
        MOVLW 0X3E              ;SET UP DELAY COUNTERS
        MOVWF TMR1H
        MOVLW 0XA4
        MOVWF TMR1L
YY  BTFSS PIR1, TMR1IF
        GOTO YY
        
 
 RETURN 
 
;********************************************************************************************************
 
        END

Any guess? the result is like 396mS

thank you again!!

milan.rajik · Nov 9, 2014

An example.

1/(1MHz/128/256) = 32.768ms

1/(1MHz/128) = 128us

99 ms / 128 us = 773.4375

TMR1H = 0x03

TMR1L = 0x05

Use mikroe Timer Calculator.

Example 4 MHz PIC16F Timer 1 99 ms Timer Interrupt.

Code C - [expand]
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//Timer1
//Prescaler 1:2; TMR1 Preload = 16036; Actual Interrupt Time : 99 ms
 
//Place/Copy this part in declaration section
void InitTimer1(){
  T1CON  = 0x11;
  TMR1IF_bit     = 0;
  TMR1H  = 0x3E;
  TMR1L  = 0xA4;
  TMR1IE_bit     = 1;
  INTCON     = 0xC0;
}
 
void Interrupt(){
  if (TMR1IF_bit){ 
    TMR1IF_bit = 0;
    TMR1H    = 0x3E;
    TMR1L    = 0xA4;
    //Enter your code here
  }
}

Convert this to ASM code.

[PIC] PIC16f887 delay 99ms

Jorge Hernández Garay

Newbie level 2

milan.rajik

Banned

Jorge Hernández Garay

Newbie level 2

milan.rajik

Banned

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[PIC] PIC16f887 delay 99ms

Jorge Hernández Garay

Newbie level 2

milan.rajik

Banned

Jorge Hernández Garay

Newbie level 2

milan.rajik

Banned

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