1 / 13

EECE.3170 Microprocessor Systems Design I

Learn how to work with PICkit, MPLAB IDE, and assembler directives for programming PIC microcontrollers. Includes sample programs and debugging techniques.

flinda
Télécharger la présentation

EECE.3170 Microprocessor Systems Design I

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. EECE.3170Microprocessor Systems Design I Instructor: Dr. Michael Geiger Fall 2016 Lecture 28: PICkit introduction

  2. Lecture outline • Announcements/reminders • HW 7 due 11/28 • HW 8: Working with PICkits—groups of up to 4 (3 preferred) • Will be due 12/9 • No lecture Wednesday, Friday (Thanksgiving) • Review • Sample programming sequences: delay, state machine • Today’s lecture: working with PICkit • Assembler directives • MPLAB IDE • Working with existing projects • Simulator • In-circuit debugging • Sample programs in assembly and C Microprocessors I: Lecture 28

  3. Review: A Delay Subroutine ; *********************************************************************************** ; TenMs subroutine and its call inserts a delay of exactly ten milliseconds ; into the execution of code. ; It assumes a 4 MHz crystal clock. One instruction cycle = 4 * Tosc. ; TenMsH equ 13 ; Initial value of TenMs Subroutine's counter ; TenMsL equ 250 ; COUNTH and COUNTL are two variables TenMs nop ; one cycle movlw TenMsH ; Initialize COUNT movwf COUNTH movlw TenMsL movwf COUNTL Ten_1 decfsz COUNTL,F ; Inner loop goto Ten_1 decfsz COUNTH,F ; Outer loop goto Ten_1 return Microprocessors I: Lecture 28

  4. Review: Strategy to “Blink” • The LEDs are toggled in sequence - green, yellow, red, green, yellow, red… • Let’s look at the lower three bits of PORTD 001=green, 010=yellow, 100=red • The next LED to be toggled is determined by the current LED. 001->010->100->001->… Microprocessors I: Lecture 28

  5. Coding “Blink” with Table Use BlinkTable movf PORTD, W ; Copy present state of LEDs into W andlw B'00000111' ; and keep only LED bits addwf PCL,F ; Change PC with PCLATH and offset in W retlw B'00000001' ; (000 -> 001) reinitialize to green retlw B'00000011' ; (001 -> 010) green to yellow retlw B'00000110' ; (010 -> 100) yellow to red retlw B'00000010' ; (011 -> 001) reinitialize to green retlw B'00000101' ; (100 -> 001) red to green retlw B'00000100' ; (101 -> 001) reinitialize to green retlw B'00000111' ; (110 -> 001) reinitialize to green retlw B'00000110' ; (111 -> 001) reinitialize to green In calling program call BlinkTable ; get bits to change into W xorwf PORTD, F ; toggle them into PORTD Microprocessors I: Lecture 28

  6. PIC microcontroller programming • Done through MPLAB IDE • Allows for generation of projects in assembly or in C • Options to generate initialization code • In-circuit debugger to view device state while hardware is actually running Microprocessors I: Lecture 28

  7. PIC assembler directives • banksellabel • Changes BSR to bank containing label • Example: banksel TRISC • cblock/endc • Used to define a block of variables • org address • Indicates starting address for block of code that follows • Address 0 in simple programs (initial PC value) • #include file • Typically used to include processor-specific definitions, macros Microprocessors I: Lecture 28

  8. Example 1: Light single LED (.asm) Start: banksel TRISC ;select bank1 bcf TRISC,0 ;make C0 an output banksel LATC ;select bank2 clrf LATC ;initialize the ; LATCH by ; turning off ; everything bsf LATC,0 ;turn on LED C0 (DS1) goto $ ;sit here forever! end Microprocessors I: Lecture 28

  9. Example 1 notes (.asm) • TRISC: controls state of Port C pins • TRISC bits = 1  corresponding pins are inputs • TRISC bits = 0  corresponding pins are outputs • LATC: used for writing data to Port C • Equivalent to writing to PORTC register • Convention: for input, read PORTC; for output, write LATC • Infinite loop at end • $ symbol—special label for current instruction Microprocessors I: Lecture 28

  10. Example 1: Light single LED (C) void main(void) { TRISCbits.TRISC0 = 0; // Pin 0 = // output LATC = 0; //clear all pins to 0 LATCbits.LATC0 = 1; // turn ON LED while(1) continue; } Microprocessors I: Lecture 28

  11. Example 1 notes (C) • Can access entire registers by name • To access individual bits, use form: regnamebits.regname# • Example:TRISCbits.TRISC0 = 0; Microprocessors I: Lecture 28

  12. Running program • Choose target device under File  Project Properties • Either use PICkit3 or Simulator • Compilation • Clean and Build • Make and Program Device (PICkit3 only) • Separate options required for debug configuration • Click arrow on right of button to build/make for debug • Window  PIC Memory Views • Allows you to view file registers and/or SFRs Microprocessors I: Lecture 28

  13. Final notes • Next time: • Working with delay • Reminders: • HW 7 due 11/28 • HW 8: Working with PICkits—groups of up to 4 (3 preferred) • Will be due 12/9 • No lecture Wednesday, Friday (Thanksgiving) Microprocessors I: Lecture 28

More Related