Assembly RSS Assembly RSS

Please help with the assembly code

Reply

•
•
Join Date: Oct 2005
Posts: 11
Reputation: perpetual_dream is an unknown quantity at this point 
Solved Threads: 0
perpetual_dream perpetual_dream is offline Offline
Newbie Poster

Please help with the assembly code

 
0
  #1
Jun 2nd, 2006
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) 
  1. ;Tutorial 7_5
  2. ;Serial routines - display received bytes on LED's
  3. ;Nigel Goodwin 2003
  4.  
  5. 	LIST	p=16F628		;tell assembler what chip we are using
  6. 	include "P16F628.inc"		;include the defaults for the chip
  7. 	ERRORLEVEL	0,	-302	;suppress bank selection messages
  8. 			;sets the configuration settings (oscillator type etc.)
  9.  
  10.  
  11.  
  12.  
  13. 		cblock	0x20			;start of general purpose registers
  14. 			count			;used in looping routines
  15. 			count1			;used in delay routine
  16. 			counta			;used in delay routine
  17. 			countb			;used in delay routine
  18. 			Xmit_Byte        	;holds byte to xmit
  19.             		Rcv_Byte        	;holds received byte 
  20.             		Bit_Cntr        	;bit counter for RS232
  21.             		Delay_Count        	;delay loop counter
  22. 		endc
  23.  
  24. SER_PORT	Equ	PORTA
  25. SER_TRIS	Equ	TRISA
  26. SER_IN		Equ	0x07
  27. SER_OUT	Equ	0x06
  28. LED_PORT	Equ	PORTB
  29. LED_TRIS	Equ	TRISB
  30.  
  31. 		org	0x0000
  32.  
  33. Start		movlw	0x07
  34. 		movwf	CMCON		      ;turn comparators off (make it like a 16F84)
  35.  
  36. Initialise	clrf	count
  37. 		clrf	PORTA
  38. 		clrf	PORTB
  39. 	        BSF     STATUS, RP0           ;select bank 1	
  40. 		clrf	LED_TRIS	      ;make LED_Port all outputs
  41. 	        BCF     STATUS, RP0           ;select bank 0
  42. 		call	SER_INIT	      ;initialise serial port
  43. Loop		call	Rcv_RS232
  44. 		movwf	LED_PORT	      ;transfer byte to LED's
  45. 		call	XMIT_RS232	      ;echo character back
  46. 		goto	Loop
  47.  
  48.  
  49. ;Serial routines
  50.  
  51. SER_INIT
  52.             BSF     STATUS, RP0           ;select bank 1
  53.             BCF     SER_TRIS, SER_OUT     ;set B6 as an output
  54.             BSF     SER_TRIS, SER_IN      ;set B7 as an input
  55.             BCF     STATUS, RP0           ;select bank 0
  56.             BSF     SER_PORT, SER_OUT     ;set SER_OUT high
  57.             RETURN
  58.  
  59. XMIT_RS232  MOVWF   Xmit_Byte             ;move W to Xmit_Byte
  60.             MOVLW   0x08                  ;set 8 bits out
  61.             MOVWF   Bit_Cntr
  62.             BCF     SER_PORT, SER_OUT
  63.             CALL    Bit_Delay
  64. Ser_Loop    RRF     Xmit_Byte , f         ;send one bit
  65.             BTFSS   STATUS    , C
  66.             BCF     SER_PORT, SER_OUT
  67.             BTFSC   STATUS    , C
  68.             BSF     SER_PORT, SER_OUT
  69.             CALL    Bit_Delay
  70.             DECFSZ  Bit_Cntr  , f         ;test if all done
  71.             GOTO    Ser_Loop
  72.             BSF     SER_PORT, SER_OUT
  73.             CALL    Bit_Delay
  74.             RETURN
  75.  
  76. Rcv_RS232   BTFSC   SER_PORT, SER_IN      ;wait for start bit
  77.             GOTO    Rcv_RS232
  78.             CALL    Start_Delay	          ;do half bit time delay
  79.             BTFSC   SER_PORT, SER_IN      ;check still in start bit
  80.             GOTO    Rcv_RS232
  81.             MOVLW   0x08                  ;set up to read 8 bits
  82.             MOVWF   Bit_Cntr
  83.             CLRF    Rcv_Byte
  84. Next_RcvBit CALL    Bit_Delay
  85.             BTFSS   SER_PORT, SER_IN
  86.             BCF     STATUS    , C
  87.             BTFSC   SER_PORT, SER_IN
  88.             BSF     STATUS    , C
  89.             RRF     Rcv_Byte  , f
  90.             DECFSZ  Bit_Cntr  , f         ;test if all done
  91.             GOTO    Next_RcvBit
  92.             CALL    Bit_Delay
  93.             MOVF    Rcv_Byte, W
  94.             RETURN
  95.  
  96. Start_Delay MOVLW   0x0C
  97.             MOVWF   Delay_Count
  98. Start_Wait  NOP
  99.             DECFSZ  Delay_Count , f
  100.             GOTO    Start_Wait
  101.             RETURN
  102.  
  103. Bit_Delay   MOVLW   0x18
  104.             MOVWF   Delay_Count
  105. Bit_Wait    NOP
  106.             DECFSZ  Delay_Count , f
  107.             GOTO    Bit_Wait
  108.             RETURN
  109.  
  110.  
  111. ;Delay routines
  112.  
  113. Long_Delay
  114. 		call	Delay255
  115. 		call	Delay255
  116. 		call	Delay255
  117. 		call	Delay255
  118. 		return
  119.  
  120. Delay255	movlw	0xff		;delay 255 mS
  121. 		goto	d0
  122. Delay100	movlw	d'100'		;delay 100mS
  123. 		goto	d0
  124. Delay50		movlw	d'50'		;delay 50mS
  125. 		goto	d0
  126. Delay20		movlw	d'20'		;delay 20mS
  127. 		goto	d0
  128. Delay10		movlw	d'10'		;delay 10mS
  129. 		goto	d0
  130. Delay1		movlw	d'1'		;delay 1mS
  131. 		goto	d0
  132. Delay5		movlw	0x05		;delay 5.000 ms (4 MHz clock)
  133. d0		movwf	count1
  134. d1		movlw	0xC7
  135. 		movwf	counta
  136. 		movlw	0x01
  137. 		movwf	countb
  138. Delay_0		decfsz	counta, f
  139. 		goto	$+2
  140. 		decfsz	countb, f
  141. 		goto	Delay_0
  142.  
  143. 		decfsz	count1	,f
  144. 		goto	d1
  145. 		retlw	0x00
  146.  
  147. ;end of Delay routines
  148.  
  149.  
  150. 		end

thnx a lot in advance
Reply With Quote Quick reply to this message  
•
•
Join Date: Mar 2006
Posts: 233
Reputation: Lord Soth is an unknown quantity at this point 
Solved Threads: 4
Lord Soth's Avatar
Lord Soth Lord Soth is offline Offline
Posting Whiz in Training

Re: Please help with the assembly code

 
1
  #2
Aug 9th, 2006
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
Best regards,
Loren Soth

Crimson K. Software _________________________________________________________________ Crimson K. Blog
Reply With Quote Quick reply to this message  
Reply

Quick Reply to Thread
This thread is more than three months old.
Perhaps start a new thread instead?
•
•
•
•
•
•
•
•
Message:
•
•
•
•



Similar Threads
Other Threads in the Assembly Forum
Thread Tools Search this Thread



3d 68hc11 6811 adress array asm assembler assembly boot bootloader buffer compression cursor debug directory division dos draw emulator endtask file int10h integer interrupt language loop nohau osdevelopment print program range read remainder shape string text tsr x86
About Us | Contact Us | Advertise | DaniWeb | Acceptable Use Policy | RSS Feed

©2003 - 2009 DaniWeb® LLC