The University of Texas at Arlington Lecture 3

Transcription

1 The University of Texas at Arlington Lecture 3 CSE 3442/5442

2 Tuesday, We Began Chapter 2, Architecture & Assembly Language Programming, Introduced the PIC WREG (Working Register) 8 bit register in PIC used the most. Illustrated the instruction: MOVLW K Move ( MOV ) the number ( L for literal ) K (example 0xA), or 10H in decimal) - into the working register ( W ). That is, load W with the value 0xA 2

3 Moving to WREG MOVLW K ; move literal value K into WREG K is an 8 value decimal or 00-FF in hex Or could move the Hex number 25 MOVLW 25H ; move 25H into WREG (WREG = 25H) 3

4 Figure 2-1. PIC WREG and ALU Using Literal Value 4

5 PIC Data Format and Directives Data Types - hex, decimal representation, etc. Instructions Tell the PIC what to do, Directives tell the Assembler what to do for executing the code. Directives EQU, ORG, #include, etc. _config directives tells assembler configuration bits for target PC (stored at H) 5

6 Figure 8-4. CONFIG Register Memory Map (Chapter 8) 6

7 Assembler Programming consists of both Instructions and Directives, see example, pp 69 SUM EQU 10H ORG 0H MOVLW 25H ;25 WREG ADDLW 0x34 ;+ 34 ADDLW 11H ADDLW D'18' ADDLW 1CH ADDLW B' ' MOVWF SUM HERE GOTO HERE END 7

8 Figure 2-8. Steps to Create a Program 8

9 Assembly/Link Process 4 files Hex (*.hex), list (*.lst), map (*.map), immediate object (*.out), debug (*.cod) Hex (*.hex) PIC ROM.hex load object,.mplab Project mcp,.mcw Workspace,.cod Code Listing,.lst Program listing,.err Debug information 9

10 From last Lecture Download MPLAB and C18 Link for MPLAB IDE Service=SS_GET_PAGE&nodeId=1406&d DocName=en019469&part=SW Link for C18 Service=SS_GET_PAGE&nodeId=1406&d DocName=en

11 Installation of Assembler/C Compiler See Users Guide 11

12 Example Build & Use of Simulator 12

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21 Figure 2-9. Program Counter in PIC18 2 MB 21

22 Figure PIC18 On-Chip Program (code) ROM Address Range 4 k 16 k 32 k 22

23 PIC18F458 Pin Diagram 23

24 Example - Powering Up PIC18F458 24

25 Programs in ROM When PIC is powered up (VCC applied to Reset Pin Chapter 8), the microcontroller begins executing instruction at location 00000h (Reset Vector). Use ORG statement for this instruction 25

26 PIC18 Program ROM Space 26

27 Program ROM Width for the PIC18 27

28 PIC18 Program ROM Contents for Program 2-1 List File Memory structured in little endian Mode 28

29 Microchip s PIC uses Harvard Architecture 29

30 SFR Window in MPLAB Simulator 30

31 File Register (Data RAM) Window in MPLAB Simulator 31

32 Program (Code) ROM Window in MPLAB Simulator 32

33 QwikFlash Board Information on QwikFlash Board at 33

34 Assignment for Tuesday Review the material in Chapter 3. Pay close attention to the instruction word sizes and target address for the BRA, GOTO, and CALL instructions, and for the Stack implementation. Using the MPLAB assembler and simulator, code and run the example on page 115 (Example 3-11), adding appropriate break points for using the simulator to display the stack contents after one of the call examples. 34

35 Note: PICF4X2 (452/458) On PICF4X2 can have up to 32K bytes of on board ROM (flash) The PICF4X2 can have up to 4K On Board Data RAM RAM or Data address space of 12 bit or 4K ROM or Code address space of 21 bits or 2 Mega Byte (General capability of PIC18 Family. 35

36 PIC Data Sheets Note, the PIC18f452 has evicedoc/39564c.pdf PIC18f458 evicedoc/41159e.pdf 36