138 lines
2.9 KiB
C
138 lines
2.9 KiB
C
#include "../config.h"
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#include "../makros.h"
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#include <avr/interrupt.h>
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#include <avr/io.h>
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#include <avr/wdt.h>
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#include "borg_hw.h"
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#define PIN_DATA PB4
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#define PIN_CLK PB3
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#define PIN_STR PB2
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// buffer which holds the currently shown frame
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unsigned char pixmap[NUMPLANE][NUM_ROWS][LINEBYTES];
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// switch to next row
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static void nextrow(uint8_t row) {
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// clear states of the preceding row
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PORTC &= 0xF0;
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PORTD &= 0x0F;
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PORTB &= 0xFC;
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// short delay loop, to ensure proper deactivation of the drivers
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unsigned char i;
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for (i = 0; i < 10; i++) {
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asm volatile("nop");
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}
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if (row == 0) {
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// row 0: initialize first shift register
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PORTB &= ~(1 << PIN_DATA); // row is active low
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PORTB |= (1 << PIN_CLK);
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PORTB &= ~(1 << PIN_CLK);
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PORTB |= (1 << PIN_DATA);
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} else {
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// remaining rows: just shift forward
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PORTB |= (1 << PIN_CLK);
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PORTB &= ~(1 << PIN_CLK);
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}
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// another delay loop, to ensure that the drivers are ready
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for (i = 0; i < 20; i++) {
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asm volatile("nop");
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}
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}
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// display a row
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static void rowshow(unsigned char row, unsigned char plane) {
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// depending on the currently drawn plane, display the row for a specific
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// amount of time
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static unsigned char const tcnt0_table[] = {244, 236, 206};
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TCNT0 = tcnt0_table[plane];
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// output data of the current row to the column drivers
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uint8_t tmp, tmp1;
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tmp = pixmap[plane][row][0];
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tmp1 = pixmap[plane][row][1];
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PORTC = (PORTC & 0xF0) | (tmp & 0x0F);
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PORTD = (PORTD & 0x0F) | (tmp & 0xF0);
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PORTB = (PORTB & 0xFC) | (tmp1 & 0x03);
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}
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// depending on the plane this interrupt gets triggered at 50 kHz, 31.25 kHz or
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// 12.5 kHz
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ISR(TIMER0_OVF_vect) {
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static unsigned char plane = 0;
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static unsigned char row = 0;
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// reset watchdog
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wdt_reset();
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// increment both row and plane
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if (++plane == NUMPLANE) {
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plane = 0;
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if (++row == NUM_ROWS) {
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row = 0;
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}
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nextrow(row);
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}
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// output current row according to current plane
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rowshow(row, plane);
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}
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void timer0_off() {
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cli();
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/*
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COLPORT1 = 0;
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COLPORT2 = 0;
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ROWPORT = 0;
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*/
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TCCR0 = 0x00;
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sei();
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}
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// initialize timer which triggers the interrupt
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static void timer0_on() {
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/* TCCR0: FOC0 WGM00 COM01 COM00 WGM01 CS02 CS01 CS00
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CS02 CS01 CS00
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0 0 0 stop
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0 0 1 clk
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0 1 0 clk/8
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0 1 1 clk/64
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1 0 0 clk/256
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1 0 1 clk/1024
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*/
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TCCR0 = 0x03; // clk/64
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TCNT0 = 0xFF - 20; // reset timer
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TIMSK |= (1 << TOIE0); // compare match Interrupt on
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}
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void borg_hw_init() {
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// set required pins to output mode
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DDRC = 0x0F; // PC0-3 - Row 0-3
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DDRD = 0xF4; // PD4-7 - Row 4-7 PD2 - ground for joy
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DDRB = 0x1F; // PB0-1 - Row 8-9 PB2-3 - STR, CLK, d
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// turn off all columns for now, clk off, d and str on
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// PC4-5, PD013 pullup on
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PORTC = 0x30;
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PORTD = 0x0B;
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PORTB = 0x14;
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timer0_on();
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// activate watchdog timer
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wdt_reset();
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wdt_enable(0x00); // 17ms watchdog
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}
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