Please help with the assembly code

Expand Post »

Hey,
I am willing to use the following code in one phase of my project. The problem is that i dont understand this assembly language, In school I took it in different form...
Mov ax, bx
out 11, AL bla bla...
here the registers is different and everything is different....
All I need is to know what are the input and output pins...
say port A0-A3 INPUT
PORT B0-B7 OUTPUT
bc i really dont know the input and output ports in the code...
the code is to be used on pic16f628 here is the microcontroller datasheet in case u need it
http://ww1.microchip.com/downloads/e...Doc/40300C.pdf
and here is the code:

Assembly Syntax (Toggle Plain Text)
;Tutorial 7_5
;Serial routines - display received bytes on LED's
;Nigel Goodwin 2003
 
	LIST	p=16F628		;tell assembler what chip we are using
	include "P16F628.inc"		;include the defaults for the chip
	ERRORLEVEL	0,	-302	;suppress bank selection messages
			;sets the configuration settings (oscillator type etc.)
 
 
 
 
		cblock	0x20			;start of general purpose registers
			count			;used in looping routines
			count1			;used in delay routine
			counta			;used in delay routine
			countb			;used in delay routine
			Xmit_Byte        	;holds byte to xmit
            		Rcv_Byte        	;holds received byte 
            		Bit_Cntr        	;bit counter for RS232
            		Delay_Count        	;delay loop counter
		endc
 
SER_PORT	Equ	PORTA
SER_TRIS	Equ	TRISA
SER_IN		Equ	0x07
SER_OUT	Equ	0x06
LED_PORT	Equ	PORTB
LED_TRIS	Equ	TRISB
 
		org	0x0000
 
Start		movlw	0x07
		movwf	CMCON		      ;turn comparators off (make it like a 16F84)
 
Initialise	clrf	count
		clrf	PORTA
		clrf	PORTB
	        BSF     STATUS, RP0           ;select bank 1	
		clrf	LED_TRIS	      ;make LED_Port all outputs
	        BCF     STATUS, RP0           ;select bank 0
		call	SER_INIT	      ;initialise serial port
Loop		call	Rcv_RS232
		movwf	LED_PORT	      ;transfer byte to LED's
		call	XMIT_RS232	      ;echo character back
		goto	Loop
 
 
;Serial routines
 
SER_INIT
            BSF     STATUS, RP0           ;select bank 1
            BCF     SER_TRIS, SER_OUT     ;set B6 as an output
            BSF     SER_TRIS, SER_IN      ;set B7 as an input
            BCF     STATUS, RP0           ;select bank 0
            BSF     SER_PORT, SER_OUT     ;set SER_OUT high
            RETURN
 
XMIT_RS232  MOVWF   Xmit_Byte             ;move W to Xmit_Byte
            MOVLW   0x08                  ;set 8 bits out
            MOVWF   Bit_Cntr
            BCF     SER_PORT, SER_OUT
            CALL    Bit_Delay
Ser_Loop    RRF     Xmit_Byte , f         ;send one bit
            BTFSS   STATUS    , C
            BCF     SER_PORT, SER_OUT
            BTFSC   STATUS    , C
            BSF     SER_PORT, SER_OUT
            CALL    Bit_Delay
            DECFSZ  Bit_Cntr  , f         ;test if all done
            GOTO    Ser_Loop
            BSF     SER_PORT, SER_OUT
            CALL    Bit_Delay
            RETURN
 
Rcv_RS232   BTFSC   SER_PORT, SER_IN      ;wait for start bit
            GOTO    Rcv_RS232
            CALL    Start_Delay	          ;do half bit time delay
            BTFSC   SER_PORT, SER_IN      ;check still in start bit
            GOTO    Rcv_RS232
            MOVLW   0x08                  ;set up to read 8 bits
            MOVWF   Bit_Cntr
            CLRF    Rcv_Byte
Next_RcvBit CALL    Bit_Delay
            BTFSS   SER_PORT, SER_IN
            BCF     STATUS    , C
            BTFSC   SER_PORT, SER_IN
            BSF     STATUS    , C
            RRF     Rcv_Byte  , f
            DECFSZ  Bit_Cntr  , f         ;test if all done
            GOTO    Next_RcvBit
            CALL    Bit_Delay
            MOVF    Rcv_Byte, W
            RETURN
 
Start_Delay MOVLW   0x0C
            MOVWF   Delay_Count
Start_Wait  NOP
            DECFSZ  Delay_Count , f
            GOTO    Start_Wait
            RETURN
 
Bit_Delay   MOVLW   0x18
            MOVWF   Delay_Count
Bit_Wait    NOP
            DECFSZ  Delay_Count , f
            GOTO    Bit_Wait
            RETURN
 
 
;Delay routines
 
Long_Delay
		call	Delay255
		call	Delay255
		call	Delay255
		call	Delay255
		return
 
Delay255	movlw	0xff		;delay 255 mS
		goto	d0
Delay100	movlw	d'100'		;delay 100mS
		goto	d0
Delay50		movlw	d'50'		;delay 50mS
		goto	d0
Delay20		movlw	d'20'		;delay 20mS
		goto	d0
Delay10		movlw	d'10'		;delay 10mS
		goto	d0
Delay1		movlw	d'1'		;delay 1mS
		goto	d0
Delay5		movlw	0x05		;delay 5.000 ms (4 MHz clock)
d0		movwf	count1
d1		movlw	0xC7
		movwf	counta
		movlw	0x01
		movwf	countb
Delay_0		decfsz	counta, f
		goto	$+2
		decfsz	countb, f
		goto	Delay_0
 
		decfsz	count1	,f
		goto	d1
		retlw	0x00
 
;end of Delay routines
 
 
		end
;Tutorial 7_5
;Serial routines - display received bytes on LED's
;Nigel Goodwin 2003

	LIST	p=16F628		;tell assembler what chip we are using
	include "P16F628.inc"		;include the defaults for the chip
	ERRORLEVEL	0,	-302	;suppress bank selection messages
			;sets the configuration settings (oscillator type etc.)




		cblock	0x20			;start of general purpose registers
			count			;used in looping routines
			count1			;used in delay routine
			counta			;used in delay routine
			countb			;used in delay routine
			Xmit_Byte        	;holds byte to xmit
            		Rcv_Byte        	;holds received byte 
            		Bit_Cntr        	;bit counter for RS232
            		Delay_Count        	;delay loop counter
		endc

SER_PORT	Equ	PORTA
SER_TRIS	Equ	TRISA
SER_IN		Equ	0x07
SER_OUT	Equ	0x06
LED_PORT	Equ	PORTB
LED_TRIS	Equ	TRISB

		org	0x0000

Start		movlw	0x07
		movwf	CMCON		      ;turn comparators off (make it like a 16F84)

Initialise	clrf	count
		clrf	PORTA
		clrf	PORTB
	        BSF     STATUS, RP0           ;select bank 1	
		clrf	LED_TRIS	      ;make LED_Port all outputs
	        BCF     STATUS, RP0           ;select bank 0
		call	SER_INIT	      ;initialise serial port
Loop		call	Rcv_RS232
		movwf	LED_PORT	      ;transfer byte to LED's
		call	XMIT_RS232	      ;echo character back
		goto	Loop


;Serial routines

SER_INIT
            BSF     STATUS, RP0           ;select bank 1
            BCF     SER_TRIS, SER_OUT     ;set B6 as an output
            BSF     SER_TRIS, SER_IN      ;set B7 as an input
            BCF     STATUS, RP0           ;select bank 0
            BSF     SER_PORT, SER_OUT     ;set SER_OUT high
            RETURN

XMIT_RS232  MOVWF   Xmit_Byte             ;move W to Xmit_Byte
            MOVLW   0x08                  ;set 8 bits out
            MOVWF   Bit_Cntr
            BCF     SER_PORT, SER_OUT
            CALL    Bit_Delay
Ser_Loop    RRF     Xmit_Byte , f         ;send one bit
            BTFSS   STATUS    , C
            BCF     SER_PORT, SER_OUT
            BTFSC   STATUS    , C
            BSF     SER_PORT, SER_OUT
            CALL    Bit_Delay
            DECFSZ  Bit_Cntr  , f         ;test if all done
            GOTO    Ser_Loop
            BSF     SER_PORT, SER_OUT
            CALL    Bit_Delay
            RETURN

Rcv_RS232   BTFSC   SER_PORT, SER_IN      ;wait for start bit
            GOTO    Rcv_RS232
            CALL    Start_Delay	          ;do half bit time delay
            BTFSC   SER_PORT, SER_IN      ;check still in start bit
            GOTO    Rcv_RS232
            MOVLW   0x08                  ;set up to read 8 bits
            MOVWF   Bit_Cntr
            CLRF    Rcv_Byte
Next_RcvBit CALL    Bit_Delay
            BTFSS   SER_PORT, SER_IN
            BCF     STATUS    , C
            BTFSC   SER_PORT, SER_IN
            BSF     STATUS    , C
            RRF     Rcv_Byte  , f
            DECFSZ  Bit_Cntr  , f         ;test if all done
            GOTO    Next_RcvBit
            CALL    Bit_Delay
            MOVF    Rcv_Byte, W
            RETURN

Start_Delay MOVLW   0x0C
            MOVWF   Delay_Count
Start_Wait  NOP
            DECFSZ  Delay_Count , f
            GOTO    Start_Wait
            RETURN

Bit_Delay   MOVLW   0x18
            MOVWF   Delay_Count
Bit_Wait    NOP
            DECFSZ  Delay_Count , f
            GOTO    Bit_Wait
            RETURN


;Delay routines

Long_Delay
		call	Delay255
		call	Delay255
		call	Delay255
		call	Delay255
		return

Delay255	movlw	0xff		;delay 255 mS
		goto	d0
Delay100	movlw	d'100'		;delay 100mS
		goto	d0
Delay50		movlw	d'50'		;delay 50mS
		goto	d0
Delay20		movlw	d'20'		;delay 20mS
		goto	d0
Delay10		movlw	d'10'		;delay 10mS
		goto	d0
Delay1		movlw	d'1'		;delay 1mS
		goto	d0
Delay5		movlw	0x05		;delay 5.000 ms (4 MHz clock)
d0		movwf	count1
d1		movlw	0xC7
		movwf	counta
		movlw	0x01
		movwf	countb
Delay_0		decfsz	counta, f
		goto	$+2
		decfsz	countb, f
		goto	Delay_0

		decfsz	count1	,f
		goto	d1
		retlw	0x00

;end of Delay routines


		end

thnx a lot in advance

Similar Threads

assembly code alteration for real time clock controller in Assembly
Reverse String - Assembly Language in Assembly
What resulit of this code?! in Assembly
Question: Where are good Assembly Compilers? in Assembly
Please AnyBody Can Help Me To Build Assembly Code Infix To Postfix It So Hard T_T in Assembly

perpetual_dream

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

11 posts
since Oct 2005

Permalink

Aug 9th, 2006

Re: Please help with the assembly code

Hi,

I suggest you to download the main PIC 16F84A manual. (or the one related to your PIC) There you will see a list of registers and opcodes. Actually for PIC registers is like memory (there are a lot of theme) and the only register is working register which is W. For example you can't move a value to a register directly you have to load it to working register first : movlw .01010101; movwf TRISA
The TRIS_ registers adjust wether the pins of the related port (TRISA -> PORTA) are to be used for input or output. (not both are possible for all port/pins) There also are two memory (register) banks you have to set

BSF STATUS, RP0 ; bit set status register bit RP0 to select bank 1
clrf TRISA ;make PORTA all pins outputs
BCF STATUS, RP0 ;select back bank 0

PORTA,PORTB,... are on bank 0 and TRISA, TRISB, ... are on bank 1 (check register map on the reference)

clrf PORTA; clear all bits/pins of PORTA

Those are the basics, post if you need any more knowledge.

Loren Soth

Lord Soth

Reputation Points: 28

Solved Threads: 4

Posting Whiz in Training

Offline

233 posts
since Mar 2006

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in Assembly Forum Timeline: Segmentation fault || Istruction OUT

Next Thread in Assembly Forum Timeline: OOPic Microcontroller - Assembly Language Programming

DaniWeb Message

Cancel Changes

User Name
Password