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151 kaklik 1
;       Module Name: CanInterface.S
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;       Module Date: 04/14/2004
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;       Module Auth: John O.
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;
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;       Description: This module provides the low-level interface
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;       to the OV6620 camera hardware.  It is responsible for
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;   	acquiring each pixel block (RG,GB), performing the mapping
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;       into an actual color (orange, purple, etc), run-length
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;       encoding the data, and storing the info off to the appropriate
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;       line buffer.  This routine is synchronized with the pixel data
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;       so that no polling of the camera data needs to be done (the
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;       OV6620 is clocked off of the same crystal source as the mega8,
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;       thus providing inherent synchronization between the two).
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#include <avr/io.h>
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#define PCLK_INTERRUPT_ENABLE_MASK  $40
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#define PCLK_INTERRUPT_DISABLE_MASK $BF
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        .section .text
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        .global CamInt_waitForNewFrame
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		.global CamInt_acquireLine
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		.global SIG_INTERRUPT0
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		.global SIG_INTERRUPT1
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;*****************************************************************		
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;   	Function Name: CamInt_waitForNewFrame
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;       Function Description: This function is responsible for
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;       going to sleep until a new frame begins (indicated by
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;    	VSYNC transitioning from high to low.  This will wake
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;       the "VSYNC sleep" up and allow it to continue with 
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;       the acquireLine function, where the system waits for
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;       a "PCLK sleep" that we use to synchronize with the
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;       data.  
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;       Inputs:  none
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;       Outputs: none
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;       NOTES: This function doesn't really return...it sorta just
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;       floats into the acquireLine function after the "VSYNC sleep"
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;       is awoken.
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;*****************************************************************
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CamInt_waitForNewFrame:
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		sleep     			; sleep mode already set to sleep idle
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CamInt_acquireLine:
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		in 	r1,_SFR_IO_ADDR(GICR)  ;enable the PCLK interrupt
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		or 	r1,PCLK_INTERRUPT_ENABLE_MASK
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		out	_SFR_IO_ADDR(GICR),r1
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		sleep
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		in	r1,_SFR_IO_ADDR(GICR)  ;disable the PCLK interrupt
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		and	r1,PCLK_INTERRUPT_DISABLE_MASK
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		out	_SFR_IO_ADDR(GICR),r1
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_acquirePixelBlock:		
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_exit:
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		ret
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SIG_INTERRUPT0:
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		; This will wake us up when VSYNC transitions low...we just want to return
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		reti
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SIG_INTERRUPT1:
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		; This will wake us up when PCLK transitions low...we just want to return
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		reti
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        .global __vector_default                ; Note [10]
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__vector_default:
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        reti
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        .end