Subversion Repositories svnkaklik

;       Module Name: CanInterface.S

;       Module Date: 04/14/2004

;       Module Auth: John O.

;

;       Description: This module provides the low-level interface

;       to the OV6620 camera hardware.  It is responsible for

;   	acquiring each pixel block (RG,GB), performing the mapping

;       into an actual color (orange, purple, etc), run-length

;       encoding the data, and storing the info off to the appropriate

;       line buffer.  This routine is synchronized with the pixel data

;       so that no polling of the camera data needs to be done (the

;       OV6620 is clocked off of the same crystal source as the mega8,

;       thus providing inherent synchronization between the two).

#include <avr/io.h>

#define PCLK_INTERRUPT_ENABLE_MASK  $40

#define PCLK_INTERRUPT_DISABLE_MASK $BF

        .section .text

        .global CamInt_waitForNewFrame

		.global CamInt_acquireLine

		.global SIG_INTERRUPT0

		.global SIG_INTERRUPT1

;*****************************************************************		

;   	Function Name: CamInt_waitForNewFrame

;       Function Description: This function is responsible for

;       going to sleep until a new frame begins (indicated by

;    	VSYNC transitioning from high to low.  This will wake

;       the "VSYNC sleep" up and allow it to continue with 

;       the acquireLine function, where the system waits for

;       a "PCLK sleep" that we use to synchronize with the

;       data.  

;       Inputs:  none

;       Outputs: none

;       NOTES: This function doesn't really return...it sorta just

;       floats into the acquireLine function after the "VSYNC sleep"

;       is awoken.

;*****************************************************************

CamInt_waitForNewFrame:

		sleep     			; sleep mode already set to sleep idle

CamInt_acquireLine:

		in 	r1,_SFR_IO_ADDR(GICR)  ;enable the PCLK interrupt

		or 	r1,PCLK_INTERRUPT_ENABLE_MASK

		out	_SFR_IO_ADDR(GICR),r1

		sleep

		in	r1,_SFR_IO_ADDR(GICR)  ;disable the PCLK interrupt

		and	r1,PCLK_INTERRUPT_DISABLE_MASK

		out	_SFR_IO_ADDR(GICR),r1

_acquirePixelBlock:		

_exit:

		ret

SIG_INTERRUPT0:

		; This will wake us up when VSYNC transitions low...we just want to return

		reti

SIG_INTERRUPT1:

		; This will wake us up when PCLK transitions low...we just want to return

		reti

        .global __vector_default                ; Note [10]

__vector_default:

        reti

        .end