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/* Copyright 2020 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* LCD driver for I2C LCD 2004.
*/
#include "i2c.h"
#include "lcd.h"
#include "timer.h"
struct lcd_state_info {
uint8_t addr;
uint8_t displayfunction;
uint8_t displaycontrol;
uint8_t backlightval;
};
static struct lcd_state_info state = {
.addr = LCD_SLAVE_ADDR,
.backlightval = LCD_BACKLIGHT,
.displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5X8DOTS,
};
/************ low level data pushing commands **********/
/* write either command or data */
static void expander_write(uint8_t data)
{
i2c_write8(I2C_PORT_TCPC, LCD_SLAVE_ADDR, 0x00, data |
state.backlightval);
}
static void pulse_enable(uint8_t data)
{
expander_write(data | LCD_EN);/* En high */
usleep(1); /* enable pulse must be >450ns */
expander_write(data & ~LCD_EN);/* En low */
usleep(50); /* commands need > 37us to settle */
}
static void write_4bits(uint8_t value)
{
expander_write(value);
pulse_enable(value);
}
static void send(uint8_t value, uint8_t mode)
{
uint8_t highnib = value & 0xf0;
uint8_t lownib = (value << 4) & 0xf0;
write_4bits(highnib | mode);
write_4bits(lownib | mode);
}
/*********** mid level commands, for sending data/cmds */
static void command(uint8_t value)
{
send(value, 0);
}
/********** high level commands, for the user! */
void lcd_clear(void)
{
command(LCD_CLEAR_DISPLAY);/* clear display, set cursor to zero */
usleep(2000); /* this command takes a long time! */
}
void lcd_set_cursor(uint8_t col, uint8_t row)
{
int row_offsets[] = { 0x00, 0x40, 0x14, 0x54 };
command(LCD_SET_DDRAMADDR | (col + row_offsets[row]));
}
void lcd_print_char(char data)
{
send(data, LCD_RS);
}
void lcd_print_string(const char *str)
{
while (*str)
lcd_print_char(*str++);
}
/* Turn the display on/off (quickly) */
void lcd_disable_display(void)
{
state.displaycontrol &= ~LCD_DISPLAY_ON;
command(LCD_DISPLAY_CONTROL | state.displaycontrol);
}
void lcd_enable_display(void)
{
state.displaycontrol |= LCD_DISPLAY_ON;
command(LCD_DISPLAY_CONTROL | state.displaycontrol);
}
/* Turn the (optional) backlight off/on */
void lcd_disable_backlight(void)
{
state.backlightval = LCD_NO_BACKLIGHT;
expander_write(0);
}
void lcd_enable_backlight(void)
{
state.backlightval = LCD_BACKLIGHT;
expander_write(0);
}
void lcd_init(uint8_t cols, uint8_t rows, uint8_t dotsize)
{
if (rows > 1)
state.displayfunction |= LCD_2LINE;
/* for some 1 line displays you can select a 10 pixel high font */
if ((dotsize != 0) && (rows == 1))
state.displayfunction |= LCD_5X10DOTS;
/* SEE PAGE 45/46 FOR INITIALIZATION SPECIFICATION!
* according to datasheet, we need at least 40ms after power rises
* above 2.7V before sending commands. Arduino can turn on way
* before 4.5V so we'll wait 50
*/
usleep(50);
/* Now we pull both RS and R/W low to begin commands */
/* reset expanderand turn backlight off (Bit 8 =1) */
expander_write(state.backlightval);
usleep(1000);
/* put the LCD into 4 bit mode
* this is according to the hitachi HD44780 datasheet
* figure 24, pg 46
* we start in 8bit mode, try to set 4 bit mode
*/
write_4bits(0x03 << 4);
usleep(4500); /* wait min 4.1ms */
/*second try */
write_4bits(0x03 << 4);
usleep(4500); /* wait min 4.1ms */
/* third go! */
write_4bits(0x03 << 4);
usleep(150);
/* finally, set to 4-bit interface */
write_4bits(0x02 << 4);
/* set # lines, font size, etc. */
command(LCD_FUNCTION_SET | state.displayfunction);
/* turn the display on with no cursor or blinking default */
state.displaycontrol = LCD_DISPLAY_ON | LCD_CURSOR_OFF | LCD_BLINK_OFF;
lcd_enable_display();
/* clear it off */
lcd_clear();
/* Initialize to default text direction (for roman languages)
* and set the entry mode
*/
command(LCD_ENTRYMODE_SET | LCD_ENTRY_LEFT | LCD_ENTRY_SHIFT_DECREMENT);
lcd_set_cursor(0, 0);
}
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