CSC231 Lab 7 solution

Solution program for Lab #7

;;; talkToArduino.asm
;;; D. Thiebaut
;;; This program requires arduino-serial.c for handling the 
;;; communication with an Arduino diecimila.
;;; This program uses strings (msg1, msg2, msg3, etc...)
;;; that contain canned commands of the form "w d 13 1" or
;;; "r d" that the sketch on the arduino understands, and 
;;; will execute.
;;; 
;;; To assemble and run 
;;;  nasm -f elf talkToArduino.asm
;;;  gcc -o talkToArduino  arduino-serial.c  talkToArduino.o
;;;  ./talkToArduino
;;;

;;; ----------------------- EXTERN LABELS -----------------------
extern serialport_writebyte	; int function
extern serialport_write		; int function
extern serialport_read_until	; int function
extern displayBuffer		; int function
	
extern buf	
extern byte		
        
        ;; -------------------------
        ;; data segment
        ;; -------------------------
        section .data
msg1        db	"w d 13 1", 0
msg1len     equ	$-msg1
	
msg2        db	"w d 13 0", 0
msg2len     equ	$-msg2

msg3        db	"r d", 0
msg3len     equ	$-msg3

msg4        db	"w d 13 "
msg4val     db	'?', 0
msg4len     equ	$-msg4
	
        section .bss
        
        ;; -------------------------
        ;; code area
        ;; -------------------------
        section .text
        global  asm_main
asm_main:
	
	;; turn Pin 13 On/Off a few times
	mov	eax, msg1
	mov	ecx, msg1len
	call	copyMsg
	call	serialport_write

	call	delay100ms
	
	mov	eax, msg2
	mov	ecx, msg2len
	call	copyMsg
	call	serialport_write	
	
	call	delay100ms
		
	mov	eax, msg1
	mov	ecx, msg1len
	call	copyMsg
	call	serialport_write
	
	call	delay100ms
	
	mov	eax, msg2
	mov	ecx, msg2len
	call	copyMsg
	call	serialport_write	

.for	mov	ecx, 1000	; read/write switch 1000 times
	call	readPin2	; get status of Pin 2 in al
	call	setPin13	; set Pin 13 to value in al
	loop	.for
	
	;; return to C program
	
	ret

;;; ----------------------------------------------------------------
;;; copyMsg1: puts array whose address in eax  in external buffer
;;; 	      number of bytes shoudl be in ecx.
;;; ----------------------------------------------------------------
copyMsg:
	pushad
	mov	esi, eax	; source buffer
	mov	edi, buf	; destination buffer in C program
.for	mov	al, [esi]
	mov	[edi], al
	inc	esi
	inc	edi
	loop	.for
	popad
	ret
	
;;; ----------------------------------------------------------------
;;; delay 100 ms.
;;; ----------------------------------------------------------------
delay100ms:
	pushad
	mov	ecx, 100000000	; 200,000,000 cycles (assuming 2GHz)
.for	add	eax, 1		; 1 cycle
	loop	.for		; 1 cycle
	popad
	ret

;;; ----------------------------------------------------------------
;;; readPin2: sends the arduino a request for value of pins
;;;             returns '0' or '1' in al as value of Pin 2
;;; ----------------------------------------------------------------
readPin2:	
	mov	eax, msg3
	mov	ecx, msg3len	; "r d" read digital pins
	call	copyMsg		; now buf contains "r d"
	call	serialport_write
	
	call	serialport_read_until
;;;   	call	displayBuffer

;;; get the value of input pin 2 as defined in buffer
;;; which contains "d 0 0 1 0 0 0 1 0 0 0 0 0"
;;; and first 0 is Pin 2, second 0 is Pin 3, etc.
	
	mov	al, [buf+2]	; get first digit and put it
                                ; in al 
	ret

;;; ----------------------------------------------------------------
;;; SetPin13: sets pin 13 to the value '0' or '1' passed in al
;;; ----------------------------------------------------------------
setPin13:
	pushad
	mov	[msg4val],al	; and embed '0' or '1' at right place
	mov	eax, msg4
	mov	ecx, msg4len	; copy msg4 in buf
	call	copyMsg
;;; 	call    displayBuffer
	call	serialport_write; send message "w d 13 x" to arduino
	popad			; restore registers

	ret