main.c

旋转16个LED灯控制程序

       	// Back pacman, as seen from front.  We have to be a little tricky
       	// here because the two sides of the mouth will be displayed on
       	// different rotations!  So line_shift will almost certainly be
       	// opposite for each unless we are spinning fast.
      	
      	if ( (line_shift & 0x01) == 0 ) {
      	
      	  if ( (pixelNum < (PAC_OPEN)) | (pixelNum > (PAC_CLOSED_NEG)) ) {
      	  
      	    cPattern[0] = 0xFF;
      	    
      	  }
      	  
      	} else {
      	
      	  if ( (pixelNum < (PAC_CLOSED)) | (pixelNum > (PAC_OPEN_NEG)) ) {
      	  
      	    cPattern[0] = 0xFF;
      	    
      	  }

      	}

      } else if (cur_code == 0xE4) {
      
       	// pacman dying
       	
       	eeprom_addr.bytes.high_byte = (line_shift << 3) & 0xF0;
      	
      	if ( (pixelNum < eeprom_addr.bytes.high_byte) | (pixelNum > (0xFF-eeprom_addr.bytes.high_byte)) ) {
      	  
      	  cPattern[0] = 0xFF;
      	    
      	}

      } else {
      
        cPattern[0] = 0x30;
        
      }
      
      set_all(cPattern[0]);
      
      // cPattern[3] = cPattern[2] = cPattern[1] = cPattern[0];
      // clock_scroll(0);
    
    }
    
  }

}

// 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) {
  
  // 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 > 0x03)) {
  if ((sensor_timer.bytes.high_byte == 0x00) || (sensor_timer.bytes.low_byte > 0x03)) {
    
    // 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;

	// 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 LINEINC lines 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 += LINEINC;
	      
	      if (cur_line >= NUM_LINES) {
	        cur_line = 0;
	      }
	  		
        }
    
      }

    #else

      // we could do this just once when the app initializes, but
      // for now, let's do it here.  Later we'll move it.
    
	  cur_line = line_shift = 0;
	  
    #endif

	// read in the code, and if need be, the pixel data
	
	cur_code = pgm_read_byte(&lines[cur_line]);

	if (cur_code < 0x80) {
	  
	  memcpy_P(cPattern,&patterns[cur_code],6);

	} else if (cur_code >= 0xF0) {
	
	  // eeprom bitmap read; because of my current rotation order, we read
	  // the bytes in reverse order
	  
	  #ifdef CLOCKWISE
	  
	    eeprom_addr.bytes.high_byte = cur_code & 0x0F;
	    eeprom_addr.bytes.low_byte = 0x00;
	  
	  #else
	  
	    eeprom_addr.bytes.high_byte = (cur_code & 0x0F) | 0x03;
	    eeprom_addr.bytes.low_byte = 0xFC;
	  
	  #endif
	  
	}

    pixelNum = 255;		// will wrap to 0, the first pixel
    
    // Start TIMER1 on its merry way...
      
    TCCR1B |= _BV(CS10);		// increment at clock/1
    TIMSK |= _BV(OCIE1A);		// enable interrupt when it matches OCR1A
    
  } else {
    
    // Since we don't have a valid setting for the rotation
    // speed, set a couple of LEDs to let the human know we
    // aren't dead yet, and turn off the timer.
      
    set_all(~0x0F);
      
    TCCR1B &= ~_BV(CS10);		// no incrementing = no interrupting
    
    // reset the line timers so that when we get a valid spinup,
    // they will start clocking the lines across the display
    
    line_timer = SCROLLSPEED;		// delay figure, will trigger wrap
    line_shift = 0x0f;				// subcharacter shift, will trigger wrap
    
    #if NUM_LINES > 0
    
      cur_line = NUM_LINES-1;			// will wrap to first line
    
    #else
    
      cur_line = 0;
      
    #endif
    
  }   
    
  // Whether we're displaying or not, we reset sensor_timer so we can
  // time the next revolution.
    
  sensor_timer.word = 0;

  }
  
  // Finally, reset hall_debounce so we won't execute the timer reset code
  // until the Hall Effect sensor hasn't bothered us for a reasonable while.
  
  hall_debounce = 0;
  
  // *** PORTB &= ~0x8;

}


// Initialize the IO pins on the ATMEL.

void ioinit(void) {

  // Set the data direction for the PORTD and PORTB pins; see the
  // circuit diagram for more information on this.
  
  DDRD = 0x73; // input on PD2 (button), PD3 (sensor), all other output
  DDRB = 0xDF; // input on MOSI/DI (for SPI), all others output

  // Deselect EEPROM.  Not being an EE, I'm not going to worry about
  // how the ATMEL talks to the EEPROM.  It's black magic.
  
  PORTB = _BV(SPIEE_CS);

  // Just above, we set PD2 and PD3 to input.  If we now set those
  // bits to 1, they set into pullup mode (again, not EE, claim
  // ignorance), which is essential for them to work.  We also set
  // the SENSORPOWER bit to 1, which sends out little dribbles of
  // electrons to the hall effect sensor (see circuit diagram)
  //
  // Finally, we write 0's to the FRONT and BACK pins, which control
  // which bank of 30 LEDs we are talking to.  Having both of these
  // on at the same time probably causes horrible things to happen.
  
  PORTD = (_BV(BUTTON) | _BV(SENSOR) | _BV(SENSORPOWER))  
    & ~_BV(FRONT) & ~_BV(BACK);

  // Rather than poll to see when the hall effect sensor and
  // button are pressed, we configure an interrupt handler.  If you
  // look at the circuit diagram, you'll see that PD3 and PD2, which
  // are wired to SENSOR IN and BUTTON IN, do double-duty as INT1
  // and INT0.  They are both SUPPOSEDLY set to interrupt on the
  // falling edge of a pulse from the devices.  (Page 63)
  
  // POSSIBLE BUG: ISC0{1,0} seems to be being set to 00, not 10
  // as ISC1{1,0} is being set to.  So ISC0 will trigger when
  // the button interrupt line goes low.  Either this is a bug,
  // or the original comment was not correct (likely, IMHO)
  
  MCUCR = _BV(ISC11) & ~_BV(ISC01) & ~_BV(ISC00) &  ~_BV(ISC10);

  // Activate the interrupts by setting the General Interrupt Mask
  // Register (Page 63)
  
  GIMSK = _BV(INT1) | _BV(INT0);

  // The ATMEL has built-in timers that can trigger an interrupt.
  // SpokePOV uses them to update the LEDs 256 times per rotation.
  
  // Timer 0 is set to update at a rate system-clock / 256 and
  // interrupt when it overflows (8 bit).  This means that it
  // triggers every 65536 cycles.
  
  TCCR0A = 0;				// normal, overflow (count up to 256 == num pixels)
  TCCR0B = _BV(CS02);		// clk/256
  TIMSK |= _BV(TOIE0);		// turn on overflow interrupt
  
  // Timer 1 (T1) is the pixel timer, which is used to update the
  // LEDs 256 times per rotation.  It's set up as a normal timer
  // as well.  See Page 108&71; it is apparently being set into CTC
  // mode 4.  This means that the counter is compared to a 16-bit value
  // and interrupts when it reaches this value.
  //
  // Adjusting this value is how the SpokePOV compensates for
  // changes in the rotation speed of the device.
  //
  // Note that at this point, the timer is initialized, but not
  // activated.
  
  TCCR1A = 0;
  TCCR1B = _BV(WGM12);

  // Clear the debounce values, which I haven't sussed out yet.
  
  hall_debounce = 0;
  sensor_timer.word = 0;
  
}

int main(void) {

  uint8_t cmd;			// the reason we reset

  // MCUSR is the MCU Status Register (page 40).  It tells us
  // why we reset, and a reset is the only way to get here.
  
  cmd = MCUSR;
  
  // The first order of business is to tell the chip that
  // we've got things under control.
  
  MCUSR = 0;
  
  // Turn on watchdog timer immediately, this protects against
  // a 'stuck' system by resetting it.
  
  // WDTCSR is the Watchdog Timer Control Register (page 45).
  // We set it so that it'll generate a watchdog interrupt
  // every second.  The idea is that if things mess up,
  // the watchdog will kickstart us.
  
  WDTCSR = _BV(WDE) | _BV(WDP2) | _BV(WDP1); // 1 second
  
  // Initialize the various pins of the ATMEL, and set up
  // the interrupts.
  
  ioinit();
  
  // Show that we are active.
  
  set_all(~0x01);

  // enable the interrupts.  I think this is not needed
  // since it'll immediately be done by the loop, below.
  
  sei();
  
  // Loop until we timeout, at which point the ATMEL is
  // put to sleep.  If the communications routine timed
  // out, or the user pressed the button for >500ms,
  // then sensor_timer will be 0xFFFF and we'll immediately
  // sleep.
  
  // Change to for (;;) to see if it makes any difference
  
  for (;;) {
  
    // Reset the watchdog Timer.
    //
    // QUESTION: What's with toggling the PD0 output line here?
    // it doesn't seem to be connected to anything according to
    // the circuit diagram...
    
    // *** PORTD |= 0x1;
    asm("wdr");
    // *** PORTD &= ~0x1;

	// If the sensor_timer (incremented by TIMER0) maxes out
	// (in about 3 minutes), then sleep everything.
	
    if (sensor_timer.bytes.high_byte == 0xFF) {
      
      // Avoid pesky interruptions
      
      cli();
      
      // Turn off all LEDs - I guess LED 0 is one of the "invisible ones"
      
      set_all(0xFF);
      
      // Turn off power to the Hall Effect sensor.
      
      SENSOR_PORT &= ~_BV(SENSORPOWER);
      
      // Deselect EEPROM
      
      SPIEE_CS_PORT |= _BV(SPIEE_CS);      // pull CS high to deselect
      
      // Turn off Watchdog (must be restarted when we get the wakeup)
      // Wakeup will be via the button interrupt.
      
      WDTCSR |= _BV(WDCE) | _BV(WDE);
      WDTCSR = 0;
      MCUCR |= _BV(SM1) | _BV(SM0) | _BV(SE);
      
      // Re-enable interrupts so we can get the wakeup!
      
      sei();
     
      // Go into sleep mode
      
      asm("sleep");
      
    } else {
              	
      sei();
           
    }
          
  }
  
  // *** PORTD |= 0x2;
}