caminterfaceasm.s

The AVRcam source files were built using the WinAVR distribution (version 3.3.1 of GCC). I haven t

							      ; current pixel run
		in	pixelCount,_SFR_IO_ADDR(TCNT1L)	; get the current TCNT1 value 
		mov   pixelRunStart,pixelCount	      ; reload pixelRunStart for the
							      ; next run
		sub	pixelCount,tmp2     		; pixelCount = TCNT1L - pixelRunStart
										
		st	X+,lastColor			; record the color run in the current line buffer
		st	X+,pixelCount			; with its length
		mov	lastColor,color			; set lastColor so we can figure out when it changes
		
		nop					; waste one more cycle for a total of 16
		rjmp	_acquirePixelBlock	
		
; _cleanUpTrackingLine is used to write the last run length block off to the currentLineBuffer so
; that all 176 pixels in the line are accounted for.
_cleanUpTrackingLine:		
		ldi	pixelCount,0xFF		      ; the length of the last run is ALWAYS 0xFF minus the last
		sub	pixelCount,pixelRunStart      ; pixelRunStart
		
		inc	pixelCount		      ; increment pixelCount since we actually need to account
						      ; for the overflow of TCNT1
										
		st	X+,color		      ; record the color run in the current line buffer
		st	X,pixelCount		
		rjmp	_cleanUp
		
_cleanUpDumpLine:		
		; NOTE: If serial data is received, to interrupt the tracking of a line, we'll
		; get a EV_SERIAL_DATA_RECEIVED event, and the T bit set so we will end the
		; line's processing...however, the PCLK will keep on ticking for the rest of
		; the frame/line, which will cause the TCNT to eventually overflow and
		; interrupt us, generating a EV_ACQUIRE_LINE_COMPLETE event.  We don't want
		; this, so we need to actually turn off the PCLK counting each time we exit
		; this loop, and only turn it on when we begin acquiring lines....
        ; NOT NEEDED FOR NOW...
		;in	tmp1, _SFR_IO_ADDR(TIMSK)		        ; disable TIMER1 to stop counting
		;andi	tmp1, DISABLE_PCLK_TIMER1_OVERFLOW_BITMASK 	; external PCLK pulses
		;out	_SFR_IO_ADDR(TIMSK),tmp1			
		
_cleanUp:
		; Toggle the debug line to indicate the line is complete
		sbi   _SFR_IO_ADDR(PORTD),PD6
		cbi   _SFR_IO_ADDR(PORTD),PD6
		clt				; clear out the T bit since we have detected
						; the interruption and are exiting to handle it
_exit:
		ret
		
;*****************************************************************		
;   	Function Name: CamIntAsm_waitForNewDumpFrame
;       Function Description: This function is responsible for
;       going to sleep until a new frame begins (indicated by
;    	VSYNC transitioning from low to high.  This will wake
;       the "VSYNC sleep" up and allow it to continue with 
;       acquiring a line of pixel data to dump out to the UI.
;       Inputs:  r25 - MSB of currentLineBuffer
;                r24 - LSB of currentLineBuffer
;		     r23 - MSB of prevLineBuffer
;		     r22 - LSB of prevLineBuffer
;       Outputs: none
;       NOTES: This function doesn't really return...it sorta just
;       floats into the acquireDumpLine function after the "VSYNC sleep"
;       is awoken.
;*****************************************************************		
CamIntAsm_waitForNewDumpFrame:
		sbi	_SFR_IO_ADDR(PORTD),PD6  ; For testing...
		cbi	_SFR_IO_ADDR(PORTD),PD6
		sleep

;*****************************************************************
; REMEMBER...everything from here on out is critically timed to be
; synchronized with the flow of pixel data from the camera...
;*****************************************************************

CamIntAsm_acquireDumpLine:
		brts	_cleanUp
		sbi	_SFR_IO_ADDR(PORTD),PD6 ; For testing...
		cbi	_SFR_IO_ADDR(PORTD),PD6
		
		mov     XH,currLineBuffHigh    	; Load the pointer to the current line
		mov	XL,currLineBuffLow	; buffer into the X pointer regs

		mov	YH,prevLineBuffHigh	      ; Load the pointer to the previous line
		mov	YL,prevLineBuffLow  	      ; buffer into the Y pointer regs
		
		ldi 	tmp1,PIXEL_RUN_START_INITIAL	; set up the TCNT1 to overflow (and
		ldi 	tmp2,0xFF 			; interrupts) after 176 pixels		
		out 	_SFR_IO_ADDR(TCNT1H),tmp2		
		out 	_SFR_IO_ADDR(TCNT1L),tmp1		
		
		in	tmp1, _SFR_IO_ADDR(TIMSK)	            ; enable TIMER1 to start counting
		ori	tmp1, ENABLE_PCLK_TIMER1_OVERFLOW_BITMASK   ; external PCLK pulses and interrupt 
		out	_SFR_IO_ADDR(TIMSK),tmp1	            ; on overflow			
		
		in 	tmp1, _SFR_IO_ADDR(GICR)	; enable the HREF interrupt...remember, we
							; only use this interrupt to synchronize
							; the beginning of the line
		ori 	tmp1, HREF_INTERRUPT_ENABLE_MASK
		out	_SFR_IO_ADDR(GICR), tmp1
		
;*******************************************************************************************
;   Dump Frame handler 
;*******************************************************************************************		
		
_dumpFrame:		
		sbi	_SFR_IO_ADDR(PORTD),PD6
		sleep                                     ; ...And we wait...

		cbi	_SFR_IO_ADDR(PORTD),PD6
		in 	tmp1, _SFR_IO_ADDR(GICR)		; disable the HREF interrupt
		andi 	tmp1, HREF_INTERRUPT_DISABLE_MASK  	; so we don't get interrupted
		out	_SFR_IO_ADDR(GICR), tmp1		; while dumping the line
	
		nop		; Remember...if we ever remove the "cbi" instruction above,
				; we need to add two more NOPs to cover this
	
; Ok...the following loop needs to run in 8 clock cycles, so we can get every
; pixel in the line...this shouldn't be a problem, since the PCLK timing was
; reduced by a factor of 2 whenever we go to dump a line (this is to give us
; enough time to do the sampling and storing of the pixel data).  In addition,
; it is assumed that we will have to do some minor processing on the data right
; before we send it out, like mask off the top 4-bits of each, and then pack both
; low nibbles into a single byte for transmission...we just don't have time to
; do that here (only 8 instruction cycles :-)  )
_sampleDumpPixel:
		in	tmp1,G_PORT		      ; sample the G value                      (1)
		in	tmp2,RB_PORT		; sample the R/B value			      (1)
		st	X+,tmp1			; store to the currLineBuff and inc ptrs  (2)
		st	Y+,tmp2			; store to the prevLineBuff and inc ptrs  (2)
		brtc	_sampleDumpPixel	      ; loop back unless flag is set            (2...if not set)
                                          ;                                     ___________
                                          ;                                          8 cycles normally
																			
		; if we make it here, it means the T flag is set, and we must have been interrupted
		; so we need to exit (what if we were interrupted for serial? should we disable it?)
		rjmp	_cleanUpDumpLine

;***********************************************************
;	Function Name: <interrupt handler for External Interrupt0> 
;	Function Description: This function is responsible
;	for handling a rising edge on the Ext Interrupt 0.  This
;	routine simply returns, since we just want to wake up
;	whenever the VSYNC transitions (meaning the start of a new
;	frame).
;	Inputs:  none
;	Outputs: none
;***********************************************************
SIG_INTERRUPT0:
; This will wake us up when VSYNC transitions high...we just want to return
		reti
		
;***********************************************************
;	Function Name: <interrupt handler for External Interrupt1> 
;	Function Description: This function is responsible
;	for handling a falling edge on the Ext Interrupt 1.  This
;	routine simply returns, since we just want to wake up
;	whenever the HREF transitions (meaning the pixels 
;	are starting after VSYNC transitioned, and we need to
; 	start acquiring the pixel blocks
;	Inputs:  none
;	Outputs: none
;***********************************************************	
SIG_INTERRUPT1:
; This will wake us up when HREF transitions high...we just want to return
		reti
		
;***********************************************************
;	Function Name: <interrupt handler for Timer0 overflow>
;	Function Description: This function is responsible
;	for handling the Timer0 overflow (hooked up to indicate
;	when we have reached the number of HREFs required in a
;	single frame).  We set the T flag in the SREG to
;	indicate to the _acquirePixelBlock routine that it needs
;	to exit, and then set the appropriate action to take in
;	the eventList of the Executive module.
;	Inputs:  none
;	Outputs: none
;   Note: Originally, the HREF pulses were also going to
;   be counted by a hardware counter, but it didn't end up
;   being necessary
;***********************************************************
;SIG_OVERFLOW0:
;		set	      ; set the T bit in SREG
;		lds	tmp1,eventBitmask
;		ori	tmp1,EV_ACQUIRE_FRAME_COMPLETE
;		sts	eventBitmask,tmp1
;		reti
		
;***********************************************************
;	Function Name: <interrupt handler for Timer1 overflow>
;	Function Description: This function is responsible
;	for handling the Timer1 overflow (hooked up to indicate
;	when we have reached the end of a line of pixel data,
;	since PCLK is hooked up to overflow TCNT1 after 176 
;	pixels).  This routine generates an acquire line complete
;	event in the fastEventBitmask, which is streamlined for
;	efficiency reasons.
;***********************************************************
SIG_OVERFLOW1:				
		lds	tmp1,fastEventBitmask   	; set a flag indicating
		ori	tmp1,FEV_ACQUIRE_LINE_COMPLETE	; a line is complete
		sts	fastEventBitmask,tmp1
		set		; set the T bit in SREG 
		sbi	_SFR_IO_ADDR(PORTD),PD6 ; For testing...
		cbi	_SFR_IO_ADDR(PORTD),PD6 ; For testing...

		reti

; This is the default handler for all interrupts that don't
; have handler routines specified for them.
        .global __vector_default              
__vector_default:
        reti

        .end