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#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include "display.h"
#include "font.h"
uint8_t cursor_y = 0;
uint8_t cursor_x = 0;
static uint8_t i2c_transfer(uint8_t usisr_val) {
USISR = usisr_val;
// 2-wire i2c + (USICS1+USICLK = timer0 clock) + 3-wire master
uint8_t cr = (1 << USIWM1) | (1 << USICS1) | (1 << USICLK) | (1 << USITC);
do {
_delay_us(I2C_DELAY_US);
USICR = cr;
while (!(PINA & (1 << DISPLAY_SCL)))
; // Wait for next clock falling edge
_delay_us(I2C_DELAY_US);
USICR = cr;
} while (!(USISR & (1 << USIOIF)));
_delay_us(I2C_DELAY_US);
uint8_t data = USIDR;
USIDR = 0xFF;
DDRA |= (1 << DISPLAY_SDA);
return data;
}
static void i2c_init(void) {
PORTA |= (1 << DISPLAY_SDA) | (1 << DISPLAY_SCL);
DDRA |= (1 << DISPLAY_SDA) | (1 << DISPLAY_SCL);
USIDR = 0xFF;
// 2-wire i2c + (USICS1+USICLK = timer0 clock)
USICR = (1 << USIWM1) | (1 << USICS1) | (1 << USICLK);
// Start interrupt + overflow interrupt + stop interrupt + output collision
USISR = (1 << USISIF) | (1 << USIOIF) | (1 << USIPF) | (1 << USIDC);
}
void i2c_start(void) {
PORTA |= (1 << DISPLAY_SCL);
while (!(PINA & (1 << DISPLAY_SCL)))
; // Wait for next clock falling edge
_delay_us(I2C_DELAY_US);
PORTA &= ~(1 << DISPLAY_SDA); // SDA low while SCL high = START
_delay_us(I2C_DELAY_US);
PORTA &= ~(1 << DISPLAY_SCL);
PORTA |= (1 << DISPLAY_SDA);
}
void i2c_stop(void) {
PORTA &= ~(1 << DISPLAY_SDA);
_delay_us(I2C_DELAY_US);
PORTA |= (1 << DISPLAY_SCL);
while (!(PINA & (1 << DISPLAY_SCL)))
;
_delay_us(I2C_DELAY_US);
PORTA |= (1 << DISPLAY_SDA); // SDA high while SCL high = STOP
_delay_us(I2C_DELAY_US);
}
void i2c_write(uint8_t data) {
PORTA &= ~(1 << DISPLAY_SCL);
USIDR = data;
// transfer 8 bits: counter=0 overflows after 16 edges (8 clocks)
i2c_transfer((1 << USISIF) | (1 << USIOIF) | (1 << USIPF) | (1 << USIDC) |
0x00);
DDRA &= ~(1 << DISPLAY_SDA);
// transfer 1 bit: counter=0x0E overflows after 2 edges (1 clock)
i2c_transfer((1 << USISIF) | (1 << USIOIF) | (1 << USIPF) | (1 << USIDC) |
0x0E);
}
void display_cmd(uint8_t cmd) {
i2c_start();
i2c_write(OLED_ADDR);
i2c_write(0x00); // Control byte: Co=0, D/C#=0
i2c_write(cmd);
i2c_stop();
}
void display_clear(void) {
for (uint8_t page = 0; page < 8; page++) {
display_cmd(DCMD_SET_PAGE_START | page);
display_cmd(0x00);
display_cmd(DCMD_SET_START_ADDR_HIGHER_COL);
i2c_start();
i2c_write(OLED_ADDR);
i2c_write(0x40);
for (uint8_t col = 0; col < 128; col++)
i2c_write(0x00);
i2c_stop();
}
}
void display_init(void) {
i2c_init();
_delay_ms(40);
display_cmd(DCMD_DISPLAY_OFF);
display_cmd(DCMD_SET_CLOCK_DIV);
display_cmd(0x80);
display_cmd(DCMD_SET_MUX_RATIO);
display_cmd(63); // 64 rows
display_cmd(DCMD_SET_OFFSET);
display_cmd(0x00);
display_cmd(DCMD_SET_START_LINE);
display_cmd(DCMD_SET_CHARGE_PUMP);
display_cmd(DCMD_CHARGE_PUMP_ENABLE);
display_cmd(DCMD_SET_ADDRESSING_MODE);
display_cmd(DCMD_ADDR_HORIZONTAL);
display_cmd(DCMD_SET_SEGMENT_REMAP);
display_cmd(DCMD_SET_COM_SCAN_DIRECTION);
display_cmd(DCMD_SET_COM_PINS);
display_cmd(0x12);
display_cmd(DCMD_SET_CONTRAST);
display_cmd(207);
display_cmd(DCMD_SET_PRECHARGE_PERIOD);
display_cmd(0xF1);
display_cmd(DCMD_SET_VCOMH_DESELECT);
display_cmd(0x40);
display_cmd(DCMD_OUTPUT_FOLLOWS_RAM);
display_cmd(DCMD_NORMAL_MODE);
display_cmd(DCMD_DISPLAY_ON);
display_clear();
}
static uint8_t scale_column(uint8_t font_byte, uint8_t page) {
uint8_t out = 0;
for (uint8_t b = 0; b < 8; b++) {
uint8_t src = (page * 8 + b) / FONT_SCALE_Y;
if (src < FONT_GLYPH_HEIGHT && (font_byte & (1 << src)))
out |= (1 << b);
}
return out;
}
void display_draw_char(uint8_t c) {
if (c < FONT_GLYPH_FIRST_CHAR || c > FONT_GLYPH_LAST_CHAR)
return;
uint16_t offset = (uint16_t)(c - FONT_GLYPH_FIRST_CHAR) * FONT_GLYPH_WIDTH;
uint8_t pages = (FONT_GLYPH_HEIGHT * FONT_SCALE_Y + 7) / 8;
for (uint8_t p = 0; p < pages; p++) {
display_cmd(DCMD_SET_PAGE_START | ((cursor_y + p) & 0x07));
display_cmd(cursor_x & 0x0F);
display_cmd(DCMD_SET_START_ADDR_HIGHER_COL | (cursor_x >> 4));
i2c_start();
i2c_write(OLED_ADDR);
i2c_write(0x40);
for (uint8_t col = 0; col < FONT_GLYPH_WIDTH; col++) {
uint8_t glyph = pgm_read_byte(&FONT_BITMAP[offset + col]);
uint8_t scaled = scale_column(glyph, p);
for (uint8_t r = 0; r < FONT_SCALE_X; r++)
i2c_write(scaled);
}
for (uint8_t r = 0; r < FONT_SCALE_X; r++)
i2c_write(0x00);
i2c_stop();
}
cursor_x += (FONT_GLYPH_WIDTH + CHAR_SPACING) * FONT_SCALE_X;
}
void display_draw_float2(float num) {
cursor_x = 5;
cursor_y = 2;
if (num < 0) {
display_draw_char('-');
num = -num;
}
int val = (int)(num * 10); // include 1 decimal place
int digit;
uint8_t is_first = 1;
for (uint16_t i = 1000; i >= 1; i /= 10, is_first = 0) {
// 2 digits left means tis decimal time
if (i == 1)
display_draw_char('.');
digit = (val / i) % 10;
val %= i;
// if first digit is 0, draw space (tis garbage code)
if (is_first && digit == 0)
display_draw_char(' ');
else
display_draw_char(digit + '0');
}
}
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