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Added separate display firmware driver

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This commit is contained in:
Gregor Riepl 2021-03-11 12:47:38 +01:00
parent e75eca4908
commit 2d03684b6d
2 changed files with 119 additions and 0 deletions
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108
display/firmware/display.c Normal file
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#include <avr/io.h>
#include <util/delay.h>
#include "display.h"
void display_init() {
// PC5, PC6, PC7: output (VFD RS, RW, E), RS=0, RW=1, E=1
// PD: output (VFD DB) - can be switched to input (pullup not needed)
PORTC |= _BV(PC6) | _BV(PC7);
DDRC |= _BV(PC5) | _BV(PC6) | _BV(PC7);
PORTD = 0x00;
DDRD = 0xff;
}
uint8_t display_read_ir() {
// switch PD to input
DDRD = 0x00;
// E=0 (enable/clock) RS=0 (IR) RW=1 (read)
PORTC = (PORTC & ~(_BV(PC5) | _BV(PC7))) | _BV(PC6);
_delay_us(0.23);
// E=1 (enable/clock)
PORTC |= _BV(PC7);
_delay_us(0.16);
uint8_t data = PIND;
_delay_us(0.23 - 0.16);
// E=0 (enable/clock)
PORTC &= ~_BV(PC7);
_delay_us(0.01);
// reset to idle
PORTC = _BV(PC6) | _BV(PC7);
DDRD = 0xff;
return data;
}
uint8_t display_read_dr() {
// switch PD to input
DDRD = 0x00;
// E=0 (enable/clock) RS=1 (IR) RW=1 (read)
PORTC = (PORTC & ~_BV(PC7)) | (_BV(PC5) | _BV(PC6));
_delay_us(0.23);
// E=1 (enable/clock)
PORTC |= _BV(PC7);
_delay_us(0.16);
uint8_t data = PIND;
_delay_us(0.23 - 0.16);
// E=0 (enable/clock)
PORTC &= ~_BV(PC7);
_delay_us(0.01);
// reset to idle
PORTC = _BV(PC6) | _BV(PC7);
DDRD = 0xff;
return data;
}
void display_write_ir(uint8_t data) {
// E=0 (enable/clock) RS=0 (IR) RW=0 (write)
PORTC &= ~(_BV(PC5) | _BV(PC6) | _BV(PC7));
_delay_us(0.23);
// E=1 (enable/clock)
PORTC |= _BV(PC7);
// data
PORTD = data;
_delay_us(0.23);
// E=0 (enable/clock)
PORTC &= ~_BV(PC7);
_delay_us(0.01);
// reset to idle
PORTC = _BV(PC6) | _BV(PC7);
PORTD = 0x00;
}
void display_write_dr(uint8_t data) {
// E=0 (enable/clock) RS=1 (IR) RW=0 (write)
PORTC = (PORTC & ~(_BV(PC6) | _BV(PC7))) | _BV(PC5);
_delay_us(0.23);
// E=1 (enable/clock)
PORTC |= _BV(PC7);
// data
PORTD = data;
_delay_us(0.23);
// E=0 (enable/clock)
PORTC &= ~_BV(PC7);
_delay_us(0.01);
// reset to idle
PORTC = _BV(PC6) | _BV(PC7);
PORTD = 0x00;
}
bool display_wait_ready() {
// if the busy flag never goes high, we'll run into a deadlock here.
// let's put a deadline on the wait loop.
for (uint8_t i = 0; i < 100; i++) {
// read_ir() takes about 500ns
if (display_read_ir() & _BV(7)) return true;
// wait 10us until the next status read
_delay_us(10 - 0.5);
}
return false;
}
void display_write(uint8_t command, const uint8_t *data, uint8_t length) {
if (display_wait_ready()) {
display_write_ir(command);
for (uint8_t i = 0; i < length; i++) {
display_write_dr(data[i]);
}
}
}

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display/firmware/display.h Normal file
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#include <stdint.h>
#include <stdbool.h>
void display_init();
void display_write(uint8_t command, const uint8_t *data, uint8_t length);
uint8_t display_read_ir();
uint8_t display_read_dr();
void display_write_ir(uint8_t data);
void display_write_dr(uint8_t data);
bool display_wait_ready();