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; 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
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