projector.c File Reference

#include "projector.h"

Go to the source code of this file.

Macros
#define	DAC_A   (0b0 << 15)
#define	DAC_B   (0b1 << 15)
#define	DAC_GAIN_VREF   (0b1 << 13)
#define	DAC_GAIN_2VREF   (0b0 << 13)
#define	DAC_ACTIVE   (0b1 << 12)
#define	DAC_INACTIVE   (0b0 << 12)
#define	PIXEL_DMA_CHN   (0)
#define	Y_MIRROR_SPI_CHN   (1)
#define	Y_MIRROR_SPI_CONFIG   (DAC_A | DAC_GAIN_2VREF | DAC_ACTIVE)
#define	PIXEL_ON_TIME   (400)
	How many clock ticks the pixel is on. More...

Functions
void	projector_init ()
	Initialize projector peripherals, variables etc. MUST be called before calling any other projector functions! More...
void	projector_set_pixel (struct color const color, unsigned int x, unsigned int y)
	Set the color of a pixel at the specified location. More...
void	__ISR (_DMA0_VECTOR, IPL5SOFT)
void	__ISR (_CHANGE_NOTICE_VECTOR, IPL5SOFT)

Variables
struct color	projector_framebuffer [IMAGE_HEIGHT][IMAGE_WIDTH+PHASE_SHIFT_PADDING] = {0}

Macro Definition Documentation

DAC_A

#define DAC_A   (0b0 << 15)

Definition at line 34 of file projector.c.

DAC_ACTIVE

#define DAC_ACTIVE   (0b1 << 12)

Definition at line 38 of file projector.c.

DAC_B

#define DAC_B   (0b1 << 15)

Definition at line 35 of file projector.c.

DAC_GAIN_2VREF

#define DAC_GAIN_2VREF   (0b0 << 13)

Definition at line 37 of file projector.c.

DAC_GAIN_VREF

#define DAC_GAIN_VREF   (0b1 << 13)

Definition at line 36 of file projector.c.

DAC_INACTIVE

#define DAC_INACTIVE   (0b0 << 12)

Definition at line 39 of file projector.c.

PIXEL_DMA_CHN

#define PIXEL_DMA_CHN   (0)

Definition at line 41 of file projector.c.

PIXEL_ON_TIME

#define PIXEL_ON_TIME   (400)

How many clock ticks the pixel is on.

Definition at line 48 of file projector.c.

Y_MIRROR_SPI_CHN

#define Y_MIRROR_SPI_CHN   (1)

Definition at line 42 of file projector.c.

Y_MIRROR_SPI_CONFIG

#define Y_MIRROR_SPI_CONFIG   (DAC_A | DAC_GAIN_2VREF | DAC_ACTIVE)

Definition at line 43 of file projector.c.

Function Documentation

__ISR() [1/2]

void __ISR	(	_DMA0_VECTOR	,
		IPL5SOFT
	)

This interrupt is called when all of the pixels from a row have been displayed. The mirror should be moved to the next line, the Timer Gate latch reset, timer reset, and DMA configured for the next row.

We also turn off the lasers clearing the last pixel. This could also be achieved by adding an always-black pixel to the end of the row and having DMA output it, an option that should be considered based on the performance of this solution.

Definition at line 229 of file projector.c.

                                                         {
  // acknowledge the INT controller, we're servicing int
  INTClearFlag(INT_SOURCE_DMA(DMA_CHANNEL0));

  // turn off the lasers
  write_pixel(color_blank);

  current_row = (current_row + 1) % IMAGE_HEIGHT;

  // move the y-axis mirror to the next row
  update_y_axis_position(current_row);

  // reset the Timer Gate Latch
  mPORTAClearBits(BIT_3);     // set the active low reset signal
  Nop(); Nop(); Nop(); Nop(); // wait for reset to occur - 4 nops is 100ns, an
                              // upper bound on the time the signal has to be
                              // low for the latch to be happy
  mPORTASetBits(BIT_3);       // unset the active low reset signal

  // prepare the DMA to output the next row
  configure_dma_for_row(current_row);
}

__ISR() [2/2]

void __ISR	(	_CHANGE_NOTICE_VECTOR	,
		IPL5SOFT
	)

Definition at line 252 of file projector.c.

                                                               {
  if ((PORTA & BIT_4) == BIT_4) {
    // if the bit is high, the light just went off. The light disappearing is a
    // low-to-high edge.
    trigger_row();
  }

  // clear the interrupt flag
  IFS1CLR = BIT_13;
}

projector_init()

void projector_init

(

void

)

Initialize projector peripherals, variables etc. MUST be called before calling any other projector functions!

Definition at line 123 of file projector.c.

                      {
  /* Set Up Pixel CLock */

  // Open Timer1 with the following configuration:
  //  - T1_ON         :: Timer is turned on
  //  - T1_SOURCE_INT :: Clock source is internal
  //  - T1_PS_1_1     :: Prescalar is 1 to 1 (timer sees PBCLK)
  //
  // The timer's period is used to fine-tune how long each pixel lasts;
  // one pixel displayed every time the timer wraps around.
  OpenTimer1(T1_ON | T1_SOURCE_INT | T1_PS_1_1, PIXEL_ON_TIME);

  // set up the pin to reset the Gate Latch, set initially high
  // (the signal is active low)
  PORTSetPinsDigitalOut(IOPORT_A, BIT_3);
  mPORTASetBits(BIT_3);

  /* Set Up CN  */

  // see reference manual 12.3.3.1
  CNCONASET = BIT_15; // enable CN on Port A (set bit 15 of CNCON to 1)
  PORTSetPinsDigitalIn(IOPORT_A, BIT_4); // RA4 is input
  unsigned int ignore = PORTA; // clear interrupt
  IPC8SET  = ((unsigned int) 5) << 18; // set CN interrupt priority
                                       // (IPC6<20:18>=5, defaults to 0 at POR)
  IFS1CLR  = BIT_13; // clear CN interrupt flag (set bit 0 of IFS1 to 0)
  CNENASET = BIT_4;  // enable for RA4 (set bit 4 of CNENA to 1)
                     // see family data sheet 11.1.4
  IEC1SET  = BIT_13; // enable CN interrupt (set bit 0 of IEC1 to 1)

  /* Set Up DMA */

  // Set up the pins as an output
  PORTSetPinsDigitalOut(IOPORT_B, BIT_0 | BIT_1   // red
                                | BIT_2 | BIT_3   // blue
                                | BIT_4 | BIT_5); // green

  // Configure DMA interrupt vector and enable DMA interrupts on CPU
  INTSetVectorPriority(INT_VECTOR_DMA(PIXEL_DMA_CHN), INT_PRIORITY_LEVEL_5);
  INTSetVectorSubPriority(INT_VECTOR_DMA(PIXEL_DMA_CHN),
                          INT_SUB_PRIORITY_LEVEL_3);
  INTEnable(INT_SOURCE_DMA(PIXEL_DMA_CHN), INT_ENABLED);

  configure_dma_for_row(0);

  /* Set Up SPI */

  // SPI Slave Sync output on pin 26
  PPSOutput(1, RPB15, SS1);

  // SPI1 data output on pin 17
  PPSOutput(2, RPB8, SDO1);

  // SPI channel 1 channel A drives the y axis control mirror.
  // The messages we send are 16 bits long (4 control bits, 12 signal bits).
  // The config flags do the following:
  //  - SPICON_MSTEN  :: Set to master mode
  //  - SPICON_MODE16 :: Sets the word size to 16 bits
  //  - SPICON_ON     :: Module ON Control
  //  - SPICON_FRMPOL :: Polarity of frame signal
  //  - SPICON_CKP    :: Reverse clock edges
  //  - SPICON_FRMEN  :: Use automatic framing: Serial clock is always on
  //                     even when no data is being sent and Slave Select/CS
  //                     pulses before each word
  // The fpbDiv = 2 sets baud rate to Fpb / fpbDiv.
  SpiChnOpen(Y_MIRROR_SPI_CHN, SPICON_MSTEN | SPICON_MODE16 | SPICON_ON
             | SPICON_FRMPOL | SPICON_CKP | SPICON_FRMEN, 2);
}

projector_set_pixel()

void projector_set_pixel	(	struct color const	color,
		unsigned int	x,
		unsigned int	y
	)

Set the color of a pixel at the specified location.

Once a pixels value is changed, the new value will be projected the next time the pixel is output (there is no v-sync).

Parameters

color	Color to be displayed
x	Number of pixels from left side
y	Number of pixels from the top

Definition at line 205 of file projector.c.

                                                         {
  projector_framebuffer[y][x + RED_PHASE_SHIFT  ].red   = color.red;
  projector_framebuffer[y][x + GREEN_PHASE_SHIFT].green = color.green;
  projector_framebuffer[y][x + BLUE_PHASE_SHIFT ].blue  = color.blue;
}

Variable Documentation

projector_framebuffer

struct color projector_framebuffer[IMAGE_HEIGHT][IMAGE_WIDTH+PHASE_SHIFT_PADDING] = {0}

Definition at line 114 of file projector.c.