fw/lcd.c (902aa40) - mips_sys · BlinkenArea

lcd.c

/* MIPS I system
 * Copyright 2011-2012 Stefan Schuermans <stefan@blinkenarea.org>
 * Copyleft GNU public license V2 or later
 *          http://www.gnu.org/copyleft/gpl.html
 */

#include "cyc_cnt.h"
#include "lcd.h"

static volatile unsigned char *const lcd_ptr =
  (volatile unsigned char *)0x80000100;

/**
 * @brief set data to LCD
 * @param[in] data data to LCD
 */
void lcd_set_data(unsigned char data)
{
  lcd_ptr[0] = data;
}

/**
 * @brief set enable signal to LCD
 * @param[in] state state for enable signal (0 or 1)
 */
void lcd_set_e(unsigned char state)
{
  lcd_ptr[1] = state;
}

/**
 * @brief set register select signal to LCD
 * @param[in] state state for register select signal (0 or 1)
 */
void lcd_set_rs(unsigned char state)
{
  lcd_ptr[2] = state;
}

/**
 * @brief set read/write signal to LCD
 * @param[in] state state for read/write signal (0 or 1)
 */
void lcd_set_rw(unsigned char state)
{
  lcd_ptr[3] = state;
}

/** set LCD to 4 bit mode */
void lcd_set4bit(void)
{
  lcd_set_data(0x0F);
  lcd_set_e(0);
  lcd_set_rs(0);
  lcd_set_rw(0);
  cyc_cnt_delay(15 * CYC_CNT_MS);
  lcd_set_data(0x3F);
  lcd_set_e(1);
  cyc_cnt_delay(12);
  lcd_set_e(0);
  cyc_cnt_delay(4100 * CYC_CNT_US);
  lcd_set_e(1);
  cyc_cnt_delay(12);
  lcd_set_e(0);
  cyc_cnt_delay(100 * CYC_CNT_US);
  lcd_set_e(1);
  cyc_cnt_delay(12);
  lcd_set_e(0);
  cyc_cnt_delay(40 * CYC_CNT_US);
  lcd_set_data(0x2F);
  lcd_set_e(1);
  cyc_cnt_delay(12);
  lcd_set_e(0);
  cyc_cnt_delay(40 * CYC_CNT_US);
}

/**
 * @brief output a byte to LCD
 * @param[in] data if the byte is a data byte (command otherwise)
 * @param[in] byte byte to write
 */
void lcd_byte(unsigned char data, unsigned char byte)
{
  lcd_set_e(0);
  lcd_set_rs(data ? 1: 0);
  lcd_set_rw(0);
  lcd_set_data(byte | 0x0F);
  lcd_set_e(1);
  cyc_cnt_delay(12);
  lcd_set_e(0);
  cyc_cnt_delay(1 * CYC_CNT_US);
  lcd_set_data(byte << 4 | 0x0F);
  lcd_set_e(1);
  cyc_cnt_delay(12);
  lcd_set_e(0);
  cyc_cnt_delay(40 * CYC_CNT_US);
}

/** initialize LCD */
void lcd_init(void)
{
  lcd_set4bit();
  lcd_byte(0, 0x28);
  lcd_byte(0, 0x06);
  lcd_byte(0, 0x0C);
  lcd_byte(0, 0x01);
  cyc_cnt_delay(1640 * CYC_CNT_US);
}

/**
 * @brief show character
 * @param[in] line number of line (0..1)
 * @param[in] pos position in line (0..15)
 * @param[in] chr character to set
 */
void lcd_chr(unsigned int line, unsigned int pos, char chr)
{
  if (line > 1 || pos > 15)
    return;
  lcd_byte(0, 0x80 | line << 6 | pos);
  lcd_byte(1, chr);
}

/**
 * @brief show string
 * @param[in] line number of line (0..1)
 * @param[in] str string to show
 */
void lcd_str(unsigned int line, const char *str)
{
  if (line > 1)
    return;
  lcd_byte(0, 0x80 | line << 6);
  unsigned int cnt;
  for (cnt = 0; cnt < 16 && str[cnt] != 0; ++cnt)
    lcd_byte(1, str[cnt]);
  for (; cnt < 16; ++cnt)
    lcd_byte(1, ' ');
}

mips_sys

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