Good Programing Techniques

[Suraj143]

Hi all!
I think I'm going in the wrong way.I love PIC Microcontrollers and for the Language I'm using Assembley.I have a fair knowledge of programing experience.When I see a program I can understand 50%.So I want to develop my knowledge upto a standard level.I'm a self study beginner.We dont have Programing courses.No body knows about PICs in my area.I have only lectro-tech-online to ask question's

I like to ask what are the techniques you guys following when programing PIC microcontrollers?
Exlacing the header files,variables,subroutines,placing the interupts in the correct places,page boundaries and
the text format simple letters or capital letters etc....

It's shy to tell but I must tell the truth.If I'm going to write a programI just open a note pad & just write the program.
I never write the program in the MPLAB.I use MPLAB only to convert the ASM file to HEX file.(with the quick build option)

What is the correct technique,what libraries do I have to import?

How to simulate a program?(with the DELAY Loops can I use the simulator?)

Is the Assembley language ok?Do I have to shift to another language?In future is this language will be available?

Any comments will accepted having any links,Tutorials,Articles will be a great help

Thank a lot
Suraj

 

[Pommie]

I would suggest that you stick with assembler for now and try some high level languages later. Use MPLAB and the simulator. Use the templates supplied by Microchip - there is C:\Program Files\Microchip\MPASM Suite\Template\Code. Use the include file so you can do btfss STATUS,Z rather that btfss 3,2 - it is much more readable and less prone to errors.

This is what the template file looks like.

;   This file is a basic code template for assembly code generation   *
;   on the PICmicro PIC16F628A. This file contains the basic code     *
;   building blocks to build upon.                                    *
;                                                                     *
;   If interrupts are not used all code presented between the ORG     *
;   0x004 directive and the label main can be removed. In addition    *
;   the variable assignments for 'w_temp' and 'status_temp' can       *
;   be removed.                                                       *
;                                                                     *
;   Refer to the MPASM User's Guide for additional information on     *
;   features of the assembler (Document DS33014).                     *
;                                                                     *
;   Refer to the respective PICmicro data sheet for additional        *
;   information on the instruction set.                               *
;                                                                     *
;**********************************************************************
;                                                                     *
;    Filename:	    xxx.asm                                           *
;    Date:                                                            *
;    File Version:                                                    *
;                                                                     *
;    Author:                                                          *
;    Company:                                                         *
;                                                                     *
;                                                                     *
;**********************************************************************
;                                                                     *
;    Files required:                                                  *
;                                                                     *
;                                                                     *
;                                                                     *
;**********************************************************************
;                                                                     *
;    Notes:                                                           *
;                                                                     *
;                                                                     *
;                                                                     *
;                                                                     *
;**********************************************************************

	list      p=16f628A           ; list directive to define processor
	#include <p16F628A.inc>       ; processor specific variable definitions

	errorlevel  -302              ; suppress message 302 from list file

	__CONFIG   _CP_OFF & _DATA_CP_OFF & _LVP_OFF & _BOREN_OFF & _MCLRE_OFF & _WDT_OFF & _PWRTE_ON & _INTOSC_OSC_NOCLKOUT 

; '__CONFIG' directive is used to embed configuration word within .asm file.
; The lables following the directive are located in the respective .inc file.
; See data sheet for additional information on configuration word settings.




;***** VARIABLE DEFINITIONS
w_temp        EQU     0x71        ; variable used for context saving 
status_temp   EQU     0x72        ; variable used for context saving





;**********************************************************************
	ORG     0x000             ; processor reset vector
	goto    main              ; go to beginning of program
	

	ORG     0x004             ; interrupt vector location
	movwf   w_temp            ; save off current W register contents
	movf	STATUS,w          ; move status register into W register
	movwf	status_temp       ; save off contents of STATUS register

; isr code can go here or be located as a call subroutine elsewhere


	movf    status_temp,w     ; retrieve copy of STATUS register
	movwf	STATUS            ; restore pre-isr STATUS register contents
	swapf   w_temp,f
	swapf   w_temp,w          ; restore pre-isr W register contents
	retfie                    ; return from interrupt


main

; remaining code goes here

	goto	main		  ;loop forever, remove this instruction, for test only


; initialize eeprom locations

	ORG	0x2100
	DE	0x00, 0x01, 0x02, 0x03


	END                       ; directive 'end of program'

If you copy this into an MPLAB project then you can put code after the main label, compile, select MPLAB SIM, press F7 and single step through your code. At any time you can look at SFR and there is a stop watch, set a breakpoint before your delay, zero the stopwatch, set a breakpoint after the delay and the stopwatch will tell you how long your delay is. That takes longer to type than to do it! Try it.

Mike.

 

[blueroomelectronics]

Use the editor in MPLAB

• its free
• its integrated with MPLAB (you can go directly to assemble / sim / debug)
• it will color code your syntax as you type
• you can uses spaces instead of tabs (makes pasting to forums nicer)
• drag and drop editing

 

[Suraj143]

Hi thanks for the suggestions. Really a nice method template file.
I tried some experiments doing with MPLAB. But it’s giving me several error messages.

I went through the project wizard.
These two files I add to my project - f628Atemp.asm & P16F628A.inc
I wrote a small program in the f628Atemp.asm file.

After building this error message prompt.

Clean: Deleting intermediary and output files. 
Clean Warning: File "f628Atemp.err" doesn't exist. 
Clean Warning: File "C:\Documents and Settings\Suraj\Desktop\run\f628Atemp.hex" doesn't exist. 
Clean Warning: File "f628Atemp.lst" doesn't exist. 
Clean: Done. 
Executing: "C:\Program Files\Microchip\MPASM Suite\MPASM.exe" /q /p16F628A "f628Atemp.asm" /l"f628Atemp.lst" /e"f628Atemp.err" 
BUILD FAILED: Fri Apr 27 09:46:09 2007

After that I added this file 16f628a.lkr file & build it again.

I got this error message. Error - no input object files specified.

Clean: Deleting intermediary and output files. 
Clean Warning: File "f628Atemp.err" doesn't exist. 
Clean Warning: File "C:\Documents and Settings\Suraj\Desktop\run\f628Atemp.hex" doesn't exist. 
Clean Warning: File "f628Atemp.lst" doesn't exist. 
Clean: Done. Executing: "C:\Program Files\Microchip\MPASM Suite\MPASM.exe" /q /p16F628A "f628Atemp.asm" /l"f628Atemp.lst" /e"f628Atemp.err" /o"f628Atemp.o" 
Executing: "C:\Program Files\Microchip\MPASM Suite\MPLink.exe" "C:\Program Files\Microchip\MPASM Suite\LKR\16f628a.lkr"  /o"LED.cof" /M"LED.map" MPLINK 3.94, Linker 

Copyright (c) 2005 Microchip Technology Inc. 
Error - no input object files specified. 
Errors    : 1  BUILD FAILED: Fri Apr 27 09:49:28 2007

I don’t know what to do. Somebody please help me to generate a hex file nicer.

Here is my project tree.

**broken link removed**

And another question in the .INC file I see all the SFR and the bits which relevant to that registers. But the INC file won’t do anything. If I forgot any bit I just look from INC file. Is this the purpose of that file? (From the datasheet also I can see this bits so why I need this file)

Actually what is the purpose of this INC file? I have included this line in the .ASM file.
#include <p16F628A.inc>

 

[Pommie]

Let’s see if we can get you up and running with a blank asm file.

Open MPLAB.
Open the project wizard. (Next)
Select 16F628A (Next)
Select “Microchip MPASM Toolsuite” (Next)
Enter “First” for Project Name
Browse to My Documents and make a new folder called “FirstProject” (Next)
At the add files stage click Next and then Finish.

You should now have a blank project.
Do File/New to get a blank window.
Cut and paste the template file I posted earlier in this thread into the blank window.
Do File/SaveAs and save the file in the FirstProject folder and call it First.asm.
In the project window, right click on “Source Files” and add file First.asm
Press F10 and it should compile without any errors.
Enter some code after the main label and have fun.

The purpose of the include file is so you don’t have to declare all the SFR values. You no longer need to know that bit 2 of location 3 is the zero flag – you just do btfsc STATUS,Z. You can also do things like bsf T1CON,TMR1ON to turn timer 1 on etc.

Mike.

 

[Suraj143]

Thanks Mike for your suggestion I'll try to do like that.