main.c

旋转16个LED灯控制程序

volatile uint8_t pixelNum = 0;		// pixel number

#ifdef USE_LOCAL_TIMER1
  volatile uint8_t clean = 0;	    // have these values been changed outside TIMER1?
#endif

#ifdef SMOOTHSCROLL

  volatile uint16_t scrollChar = 0;	// extra scroll character

#endif

// This routine gets called every time the pixel timer runs down;
// in other words, once per "scan line", 256 times per revolution
// of the SpokePOV.  Its purpose is to update the LEDs.

SIGNAL (SIG_TIMER1_COMPA) {

  #ifdef USE_LOCALUSE_LOCAL_TIMER1
  
    uint16_t tChar;					// local copies of the values
    uint16_t bChar;
    uint8_t cNum;						
    uint8_t pNum;
  
    #ifdef SMOOTHSCROLL

      uint16_t sChar;					// extra scroll character

    #endif

    // When an interrupt routine is called, interrupts are disabled.
    // but it's important to let other interrupts interrupt us, so
    // they need to be re-enabled.
	
    sei();

    // Copy the volatile variables into their local equivalents
  
    tChar = topChar;
    bChar = botChar;
    cNum = charNum;
    pNum = pixelNum;

    #ifdef SMOOTHSCROLL
 
      sChar = scrollChar;

    #endif
    
  #else
  
    #define	tChar	topChar
    #define	bChar	botChar
    #define	cNum	charNum
    #define	pNum	pixelNum
    #define	sChar	scrollChar
    
  #endif

  // If it has been less than STANDBY_TIMEOUT seconds since the last time we
  // got a Hall Effect sensor update, then proceed as normal and
  // update the LEDs.
  
  // QUESTION: what is F_CPU?  ANSWER: FREQUENCY OF CPU (clocks/second)
  
  if (sensor_timer.bytes.high_byte < ( (F_CPU/NUM_PIXELS)/256 * STANDBY_TIMEOUT) / 256) {    
    
    // *** PORTA |= 0x1;
    
    // The first thing we do is increment our character position; this
    // is done here to avoid code duplication.  This means that the
    // Hall Effect interrupt routine must set them up so they "wrap"
    // into the first valid values.
    
    // Move to the next pixel in the character
    
    pNum++;
    
    // If we have moved off the edge of the character, then
    // we need to move to the next character
    
    if (pNum == 16) {
    
      // If we will wrap around to the first character, turn off the pixel
      // timer, clear the display, and exit.  Might speed things up a bit
      
      if (cNum == 15) {
        TCCR1B &= ~0x7;
        set_all(~0x00);
        return;
      }

      pNum = 0;					// reset to first pixel
      cNum = (cNum+1) & 0x0F;	// move, with wrap, to next character position
            
      // Now we need to reset the pointers to the correct addresses
      // in the EEPROM for the characters they display.  With the new
      // interleaved character sets, this becomes much easier
      
      tChar = (topLine[cNum]-32) << 1;		// character offset for the top char, 0-95
      
      // Ditto for bChar...
      
      bChar = (botLine[cNum]-32) << 1;
      
	  #ifdef SMOOTHSCROLL
	
		// and if smooth scrolling, sChar
		  
		sChar = (scrollLine[cNum]-32) << 1;
		  
	  #endif

    } else {
    
      // If we haven't wrapped around a character boundary, we just move
      // to the next 2-byte line in the character set, which will be 192 bytes
      // away
      
      tChar += 192;
      bChar += 192;
      
	  #ifdef SMOOTHSCROLL
		
		sChar += 192;
		
	  #endif

    }
     
    // Unfortunately, we can't do the cute "read from the EEPROM right
    // into the LEDs trick" that limor can do in SpokePOV.  We have to
    // read the data into the ATMEL and then write it out.
    
    spieeprom_read(tChar,fleds,2);		// the top 2 bytes
    spieeprom_read(bChar,fleds+2,2);	// and the bottom 2
    
    #ifdef SMOOTHSCROLL

      spieeprom_read(sChar,fleds+4,2);	// and the scroll characters

    #endif

	// However, we do have a fancy trick of our own.  If we are
	// smooth scrolling, then we clock out an extra line_shift
	// BITS, thus implementing the smooth scrolling
	
    #ifdef SMOOTHSCROLL

	  clock_scroll(line_shift);			// send 0-15 extra bits..
	
    #else

      clock_scroll(0);					// just send the 4 bytes
    
    #endif

    // Now we increment the variables.  However, we
    // only do it IF haven't been touched by some other part
    // of the code while we were displaying the pixels.  Also, we
    // turn interrupts off so that nobody else can touch them
    // while we are at it
    
    #ifdef USE_LOCAL_TIMER1
    
    cli();
    
    if (clean) {

	  topChar = tChar;
	  botChar = bChar;
	  charNum = cNum;
	  pixelNum = pNum;
	  
      #ifdef SMOOTHSCROLL

	    scrollChar = sChar;
	
      #endif

      
    } else {
    
      // Since we didn't update the data, we know it was changed, and
      // we know that next time, we CAN update the data.  So everything
      // is clean now!
      
      clean = 1;
      
    }

    sei();
    
    #endif

#ifdef DONOTCOMPILE

  // The following code is obsoleted by the fact that we turn off the
  // timer in the main code, above.
  
  } else {
    
    // We have not seen the magnet in a while, so turn off the
    // pixel timer...
    
    // *** PORTA |= 0x2;

    // Turn off this pixel timer
    // Question: this is different from the code in SIG_INT1.  Why?
    
    TCCR1B &= ~0x7;
 
    // display reason for turnoff
    
    set_all(~0x07);

    // *** PORTA &= ~0x2;

#endif

  }

  // *** PORTB &= ~0x2;
  
}

// Interrupt 0 executes when the button is pressed.

// QUESTION: unlike the pixel output interrupt, this one
// doesn't sei().  Why?

SIGNAL (SIG_INT0) {
  
  // Wait until button no longer pressed
  
  while (! (BUTTON_PIN & _BV(BUTTON))) {
  }
  
  if (sensor_timer.bytes.high_byte == 0xFF) {
    
    // so in this instance, we set the watchdog to reset us
    
    sensor_timer.bytes.high_byte = 0x00;
      
    // Re-enable the watchdog timer, then loop until
    // it fires off.
      
    WDTCSR = _BV(WDE);
    for (;;);
      
  } else {
      
    // We want to shut everything down.  Setting sensor_timer
    // to the pin value will cause both the communications
    // loop and the regular timeout loop in the main() to
    // give up, which results in the device going to sleep.
      
    sensor_timer.bytes.high_byte = 0xFF;
      
  }

}

// Interrupt 1 executes when the hall effect sensor fires

// QUESTION: unlike the pixel output interrupt, this one
// doesn't sei().  Why?

SIGNAL (SIG_INT1) {
  
  #if NUM_LINES > 0

    uint8_t cLine;		// temp var used in scroll code
 
  #endif
  
  #ifdef DYNAMIC
  
  	uint8_t dCode;		// temp var used in dynamic code
  	
  #endif

  // make sure we don't get bitten by the watchdog
  
  asm("wdr");

  // *** PORTB |= 0x8;

  // The first issue we need to deal with when the hall-effect
  // sensor tells us it sees the magnet is to avoid doing any
  // processing if we get an interrupt too soon after the previous
  // interrupt.
  
  // hall_debounce is incremented by TIMER0, which fires every 3ms
  // or so.  At the current setting of 4, this means that at least
  // 15ms must elapse per trigger, which translates to about 4000
  // rpm.
  
  if (hall_debounce > HALL_DEBOUNCE_THRESH) {


  // We know the number of ms since the last hall sensor trigger
  // and there are 128 radial 'pixels' per sweep so divide to get
  // the necessary ms between the pixel interrupts
    
  // QUESTION: 128 or 256?
    
  // Then we just make TIMER1 trigger at that rate!
    
  // Reset the Timer Count Register for TIMER1 to 0, so it will
  // begin counting up.
    
  TCNT1 = 0;
    
  // sensor_timer contains the number of TIMER0 interrupts since
  // the last time we updated TIMER1.  If it has a reasonable
  // value, then we use it to reset the TIMER1 clock.
    
  if ((sensor_timer.bytes.low_byte < 0xFF) && (sensor_timer.bytes.low_byte > 0x3)) {
    
    // TIMER1 works differently from TIMER0.  It's a 16-bit timer
    // that apparently increments at the system clock rate.
    //
    // Because TIMER0 increments at 1/256 of the clock rate, and
    // fires the interrupt only when it overflows, sensor_timer
    // is incremented once ever 256*256 cycles.
    //
    // We want TIMER1 to fire off 256 times around the loop, so
    // we can display 256 lines of pixels.  We do this by putting
    // sensor_timer into the high byte of TIMER1's comparator
    // value, and the residual of TIMER0 (what it's counted up
    // to since the last time sensor_timer was incremented) into
    // the low byte, effectively a fractional value!
    //
    // Since TIMER0 is incrementing at 1/256 of the rate of TIMER1,
    // this results in TIMER1 firing off 256 times per rotation,
    // with excellent time resolution.
    //
    // I was quite touched by the elegance of how this works out;
    // it may be able to handle the extreme RPMs of BrightSaber
    // without modification...
      
    // Set the TIMER1 comparator value.  As a hack to Limor's hack,
    // reduce the timing a little bit so that the display doesn't
    // span the full 360 degrees, thus giving us a little more time
    // around hall-effect interrupt time to do things.  An attempt
    // to get more speed, it doesn't seem to help - so back to the
    // old way of doing things.
    
    // OCR1A = ((sensor_timer << 8) | TCNT0) - (sensor_timer);
    
    // OCR1A = ((sensor_timer << 8) | TCNT0);
    
    OCR1AH = sensor_timer.bytes.low_byte;
    OCR1AL = TCNT0;
    
    // Clear the residual of TIMER0
      
    TCNT0 = 0;

	// If we are in dynamic mode and want the rev counter, increment the rev counter
	
	#ifdef DYNAMIC_REVCOUNT
	
	  // Increment the 4 byte rev counter - stored in reverse
	  // byte order
		
	  dynamicREV[0]++;
	  dCode = 0;
	  
	  while (dynamicREV[dCode] > '9') {
		dynamicREV[dCode] = '0';
		if (dCode != 3) {
		  dynamicREV[++dCode]++;			// Dont'cha just love compressed C syntax...?
		}
      }
		
	#endif
	
	// if we have only 2 lines, then we never scroll
	// otherwise, we have to move between the lines.
	// The code for no scrolling is NUM_LINES = 0
	
    #if NUM_LINES > 0

      // Check the line timer; if it has reached a particular value
      // then increment line_shift.  When that reaches 16, wrap it
      // and increment cur_line.  This system lets us be a little
      // more flexible in our timing system, and permits long delays
      // in the scrolling.
    
      if (line_timer >= SCROLLSPEED) {
    
        line_timer = line_timer - SCROLLSPEED;	// reset in a safe way that retains any residual
        line_shift = (line_shift + 1) & 0x0f;	// increment line_shift
      
        if (line_shift == 0x00) {

	      // Move down 1 line in the line list, wrapping around
	  	  // Made the mistake of using % which isn't a good thing
	  	  // on a chip without mult/div...
	  	  
	      cur_line++;
	      
	      if (cur_line == NUM_LINES) {
	        cur_line = 0;
	      }
	  
	      // Move the new first line into topLine.  Index through the
	      // lineOffsets array
	      
	      dCode = pgm_read_byte(lineOffsets+cur_line);
	  
	      memcpy_P(topLine,lines+dCode,16);
	      
	      // If we are doing dynamic data, set it if there
	      // is such data in the line.
	      
	      #ifdef DYNAMIC
	      
	        dynamicType = 0x00;					// assume no dynamic data will be shown
	        
	        dCode = pgm_read_byte(dInfo+cur_line);
	        
	        if (dCode != 0) {
	          dynamicPtr = topLine + (dCode & 0x0F);
	          dynamicType = dCode;
	        }
	        
	      #endif
	  
	      // Get the second line, which may wrap, but since we have
	      // extra entries in lineOffsets, this is not a problem!
	  
	      cLine = cur_line + 1;
	      
	      dCode = pgm_read_byte(lineOffsets+cLine);

	      memcpy_P(botLine,lines+dCode,16);
		  
	      // If we are doing dynamic data, set it if there
	      // is such data in the line.
	      
	      #ifdef DYNAMIC
	      
	        dCode = pgm_read_byte(dInfo+cLine);
	        
	        if (dCode != 0) {
	          dynamicPtr = botLine + (dCode & 0x0F);
	          dynamicType = dCode;
	        }
	        
	      #endif
	  
		  #ifdef SMOOTHSCROLL

	        // get the third line, which may wrap..
	  
	        cLine++;
	      
	        dCode = pgm_read_byte(lineOffsets+cLine);

	        memcpy_P(scrollLine,lines+dCode,16);
	    	
	        // If we are doing dynamic data, set it if there
	        // is such data in the line.