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Delay Implementation and Microcontroller Programming Techniques

This document outlines various programming techniques for implementing delays on the PIC16F887 microcontroller, specifically utilizing the DB037 development board. It provides insights into register selection, memory mapping, and assembly language routines. Key concepts include creating 1 ms delays through loops, utilizing NOP (No Operation) instructions, and understanding how to program the development environment. Additionally, it discusses peripheral interfacing with LEDs and sound output while ensuring efficient register management for proper functionality.

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Delay Implementation and Microcontroller Programming Techniques

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  1. Les 3 - onderwerpen • Hints voor ‘delay’ • Register file banks • Gebruik van het DB037 bord • Aftekenen vorige opgaves • Twee nieuwe opgaves Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  2. Een W * 1 ms delay int i = W; while( i > 0 ){ i--; Delay_1ms(); } Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  3. Een Delay_1ms • 5 MIPS dus 1 ms is 5000 instructies* • In 8 bit kan je tot 256 tellen, neem 250 • 1 keer door de lus moet dan 5000 / 250 = 20 instructies zijn Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  4. Een Delay_1ms cblock teller endc movlw D’250’ movwf teller loop: decfsz teller, f goto loop Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  5. Een paar instructies vertraging (1) loop: nop ; 17 NOPs ... nop decfsz teller, f goto loop Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  6. Een paar instructies vertraging (2) nop4: macro nop nop nop nop enmd loop: nop nop4 nop4 nop4 nop4 decfsz teller, f goto loop Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  7. Een paar instructies vertraging (3) cblock teller endc movlw D’250’ movwf teller loop: nop call delay_4 call delay_4 call delay_4 call delay_4 decfsz teller, f goto loop delay_4: return Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  8. Een paar instructies vertraging (4) cblock teller endc movlw D’250’ movwf teller loop: nop call delay_16 decfsz teller, f goto loop delay_16: call delay_4 delay_12: call delay_4 delay_8: call delay_4 delay_4: return Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  9. PIC16F887 memory map Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  10. PIC –register bank selection Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  11. DB037 Contains: • Target chip: PIC16F877 • Programmer: pickit2 clone • Power: from USB (2x), Wall-Wart, NiCad • Peripherals: LSP, LEDs (and much more) Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  12. DB037 8 LEDs Programming connector Programming activity LED Power LED reset Power source (zet de jumper rechts) Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  13. Using DB037 • Get count.zip (from my website) • Unzip to new directory (path!) • Double-click count.mcp • Edit count.asm • Assemble • Correct errors and repeat .... Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  14. an (empty) DB037 program ;================================================================ ; ; count.asm ; ;================================================================ ; initialisation etc for DB037 ; also beeps and activated the LEDs #include <DB037-01.INC> ;================================================================ ; main ;================================================================ ; put your code here ;================================================================ ; end of assembler source ;================================================================ SLEEP END Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  15. DB037-01.INC • Includes the Microchip16F877 include file (register definitions) • Sets the configuration word(s) (oa. 20 MHz crystal, external reset) • ORG 0, CBLOCK H’20’ • PORTx_SHADOW, PORTx_FLUSH (x = A,B,C,D) • WWAIT subroutine • Initialises TRIS (direction) registers • Beeps • Activates LEDS, pattern 0x55 Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  16. DB037-01.INC (1) ;================================================================ ; ; include file for DB037 for a first program ; ; beeps and activates the LEDs with a 0x55 pattern ; ;================================================================ ; select target chip and hex file format LIST p=16f887, f=inhx32 ; include target chip stuff #include <P16F887.INC> Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  17. DB037-01.INC (2) ; configuration settings __config _CONFIG1, 0x20E2 ; -debug, -LVP, -fcmen, -ieso, -boren, ; -cpd, -cp, mclre, pwtre, -wdte, HSosc __config _CONFIG2, 0x3FFF ; nothing special Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  18. DB037-01.INC (3) ; start code at 0 ORG 0 ; start variables at 0x20 CBLOCK H'20' ENDC ; skip subroutines GOTO WContinue Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  19. DB037-01.INC (4) ; =========================================================== ; shadow registers and flush subroutines FLUSH_MACRO MACRO Shadow, Port CBLOCK Shadow ENDC MOVFW Shadow MOVWF Port RETURN ENDM PORTA_FLUSH FLUSH_MACRO PORTA_SHADOW, PORTA PORTB_FLUSH FLUSH_MACRO PORTB_SHADOW, PORTB PORTC_FLUSH FLUSH_MACRO PORTC_SHADOW, PORTC PORTD_FLUSH FLUSH_MACRO PORTD_SHADOW, PORTD PORTE_FLUSH FLUSH_MACRO PORTE_SHADOW, PORTE Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  20. DB037-01.INC (5) ; =========================================================== ; WWAIT WWAIT CBLOCK WWaitCounter ENDC MOVLW 0x00 MOVWF WWaitCounter WWaitLoop CALL WWaitReturn DECFSZ WWaitCounter, f GOTO WWaitLoop WWaitReturn RETURN Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  21. DB037-01.INC (6) WContinue ; =========================================================== ; A0..A2 and D and E0..E2 are outputs BSF STATUS, RP0 MOVLW 0xD8 MOVWF ( 0x80 ^ TRISA ) MOVLW 0x00 MOVWF ( 0x80 ^ TRISD ) MOVLW 0xF8 MOVWF ( 0x80 ^ TRISE ) BCF STATUS, RP0 Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  22. DB037-01.INC (7) ; =========================================================== ; beep CBLOCK WBeepCounter ENDC CLRF WBeepCounter MOVLW H'02' MOVWF PORTE_SHADOW CALL PORTE_FLUSH WBeepLoop BSF PORTA_SHADOW, 1 CALL PORTA_FLUSH CALL WWAIT BCF PORTA_SHADOW, 1 CALL PORTA_FLUSH CALL WWAIT DECFSZ WBeepCounter, f GOTO WBeepLoop Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  23. DB037-01.INC (8) ; =========================================================== ; activate the LEDs MOVLW H'04' MOVWF PORTE_SHADOW CALL PORTE_FLUSH MOVLW H'55' ^ H'FF' MOVWF PORTD_SHADOW CALL PORTD_FLUSH ; the students' application follows ; (in the file that includes this file) Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  24. PICkit 2 V1.20 • Gebruik V1.20 !!! • Device Family > Midrange (14 bit core) Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  25. PICkit 2 V1.20 • Selecteer de .hex file die je in MPLAB hebt aangemaakt: <project name>.HEX Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  26. PICkit 2 V1.20 • Zet target 5.0V aan Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  27. PICkit 2 V1.20 • Zet programmeren van de Data EEPROM (voorlopig) uit Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  28. DB037 bordje – tel op 8 LEDs Main loop: • Tel in een variabele • Copieer die naar PORTD • Wacht 4 ms (gebruik je wacht subroutine) Allokeer je variabelen nu en voortaan op de nette manier (cblock). Hoe snel zal de meest linker LED ongeveer gaan knipperen? Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

  29. DB037 bordje – Kitt Display Maakt een ‘Kitt’ display op de 8 LEDs. (Kitt patroon is: steeds 1 LED aan, de LED die aan is ‘beweegt’ heen-en-weer). NB: 4 ms voor een stap is nu een beetje te snel! Hogeschool Utrecht / Institute for Computer, Communication and Media Technology

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