109 lines
2.4 KiB
C
109 lines
2.4 KiB
C
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#include <avr/io.h>
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#include <util/delay.h>
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#include "display.h"
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void display_init() {
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// PC5, PC6, PC7: output (VFD RS, RW, E), RS=0, RW=1, E=1
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// PD: output (VFD DB) - can be switched to input (pullup not needed)
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PORTC |= _BV(PC6) | _BV(PC7);
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DDRC |= _BV(PC5) | _BV(PC6) | _BV(PC7);
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PORTD = 0x00;
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DDRD = 0xff;
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}
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uint8_t display_read_ir() {
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// switch PD to input
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DDRD = 0x00;
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// E=0 (enable/clock) RS=0 (IR) RW=1 (read)
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PORTC = (PORTC & ~(_BV(PC5) | _BV(PC7))) | _BV(PC6);
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_delay_us(0.23);
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// E=1 (enable/clock)
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PORTC |= _BV(PC7);
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_delay_us(0.16);
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uint8_t data = PIND;
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_delay_us(0.23 - 0.16);
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// E=0 (enable/clock)
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PORTC &= ~_BV(PC7);
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_delay_us(0.01);
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// reset to idle
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PORTC = _BV(PC6) | _BV(PC7);
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DDRD = 0xff;
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return data;
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}
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uint8_t display_read_dr() {
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// switch PD to input
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DDRD = 0x00;
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// E=0 (enable/clock) RS=1 (IR) RW=1 (read)
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PORTC = (PORTC & ~_BV(PC7)) | (_BV(PC5) | _BV(PC6));
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_delay_us(0.23);
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// E=1 (enable/clock)
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PORTC |= _BV(PC7);
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_delay_us(0.16);
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uint8_t data = PIND;
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_delay_us(0.23 - 0.16);
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// E=0 (enable/clock)
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PORTC &= ~_BV(PC7);
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_delay_us(0.01);
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// reset to idle
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PORTC = _BV(PC6) | _BV(PC7);
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DDRD = 0xff;
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return data;
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}
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void display_write_ir(uint8_t data) {
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// E=0 (enable/clock) RS=0 (IR) RW=0 (write)
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PORTC &= ~(_BV(PC5) | _BV(PC6) | _BV(PC7));
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_delay_us(0.23);
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// E=1 (enable/clock)
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PORTC |= _BV(PC7);
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// data
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PORTD = data;
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_delay_us(0.23);
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// E=0 (enable/clock)
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PORTC &= ~_BV(PC7);
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_delay_us(0.01);
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// reset to idle
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PORTC = _BV(PC6) | _BV(PC7);
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PORTD = 0x00;
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}
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void display_write_dr(uint8_t data) {
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// E=0 (enable/clock) RS=1 (IR) RW=0 (write)
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PORTC = (PORTC & ~(_BV(PC6) | _BV(PC7))) | _BV(PC5);
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_delay_us(0.23);
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// E=1 (enable/clock)
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PORTC |= _BV(PC7);
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// data
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PORTD = data;
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_delay_us(0.23);
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// E=0 (enable/clock)
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PORTC &= ~_BV(PC7);
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_delay_us(0.01);
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// reset to idle
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PORTC = _BV(PC6) | _BV(PC7);
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PORTD = 0x00;
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}
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bool display_wait_ready() {
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// if the busy flag never goes high, we'll run into a deadlock here.
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// let's put a deadline on the wait loop.
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for (uint8_t i = 0; i < 100; i++) {
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// read_ir() takes about 500ns
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if (display_read_ir() & _BV(7)) return true;
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// wait 10us until the next status read
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_delay_us(10 - 0.5);
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}
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return false;
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}
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void display_write(uint8_t command, const uint8_t *data, uint8_t length) {
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if (display_wait_ready()) {
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display_write_ir(command);
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for (uint8_t i = 0; i < length; i++) {
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display_write_dr(data[i]);
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}
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}
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}
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