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147 lines
2.8 KiB
C
147 lines
2.8 KiB
C
/*
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* fw/image.c - Image sweep
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*
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* Written 2012 by Werner Almesberger
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* Copyright 2012 Werner Almesberger
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <stdbool.h>
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#include <stdint.h>
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "image.h"
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#include "sweep.h"
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struct line image[MAX_LINES];
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static uint32_t t_sw; /* cumulative number of timer ticks in sweep */
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static uint16_t wait_periods; /* number of periods to wait before image */
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static uint16_t wait_period; /* ticks in wait period */
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static uint16_t wait_short; /* ticks to wait after periods */
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static uint16_t pixel_ticks; /* number of ticks per pixel */
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static const struct line *curr_line;
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static const struct line *end_line;
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static bool forward;
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ISR(TIMER1_OVF_vect)
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{
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/* update the sweep time */
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t_sw += OCR1A;
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/* if at the end of the image, only update the time */
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if (curr_line == end_line)
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return;
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/* wait before starting the image */
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if (wait_periods) {
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if (!--wait_periods)
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OCR1A = wait_short;
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return;
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}
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/* output the next line */
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PORTB = (PORTB & 0x3f) | (curr_line->cb & 0xc0);
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PORTC = curr_line->cb;
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PORTD = curr_line->d;
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/* move to the next line */
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if (forward)
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curr_line++;
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else
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curr_line--;
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/* wait until the next pixel (or slow down if we're done) */
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if (curr_line == end_line)
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OCR1A = 0xffff;
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else
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OCR1A = pixel_ticks;
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}
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void image_sweep(const struct sweep *sweep)
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{
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TCCR1B = 0; /* stop the timer */
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cli();
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/* shut down all the LEDs, in case we're still in a sweep */
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PORTB &= 0x3f;
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PORTC = 0;
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PORTD = 0;
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/* image pointers and sweep direction */
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forward = sweep->forward;
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if (forward) {
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curr_line = image+sweep->left;
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end_line = image+sweep->right+1;
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} else {
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curr_line = image+sweep->right;
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end_line = image+sweep->left-1;
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}
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/* timing parameters */
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wait_periods = sweep->wait_ticks >> 16;
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if (wait_periods) {
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wait_short = sweep->wait_ticks;
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wait_period = 0xffff;
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/*
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* Make sure we have plenty of time to update OCR1A after an
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* interrupt.
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*/
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if (wait_short < 256) {
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wait_period -= 128;
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wait_short += wait_periods << 7;
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}
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OCR1A = wait_period;
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} else {
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OCR1A = sweep->wait_ticks;
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}
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/* prepare the hardware timer */
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t_sw = 0; /* reset the time */
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TCNT1 = 0;
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TIFR1 = 1 << TOV1; /* clear interrupt */
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/* start the timer */
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TCCR1B =
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1 << WGM13 | /* WG Mode 15, continued */
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1 << WGM12 |
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1 << CS11; /* clkIO/8 */
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}
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void sweep_init(void)
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{
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TCCR1A =
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1 << WGM11 | /* WG Mode 15 (Fast PWM to OCR1A) */
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1 << WGM10;
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TCNT1 = 0;
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TIMSK1 = 1 << TOIE1; /* enable timer interrupts */
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}
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