HD44780.c
3.24 KB
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/*
LUFA Library
Copyright (C) Dean Camera, 2019.
dean [at] fourwalledcubicle [dot] com
www.lufa-lib.org
*/
/*
Copyright 2019 Dean Camera (dean [at] fourwalledcubicle [dot] com)
Copyright 2012 Simon Foster (simon.foster [at] inbox [dot] com)
Permission to use, copy, modify, distribute, and sell this
software and its documentation for any purpose is hereby granted
without fee, provided that the above copyright notice appear in
all copies and that both that the copyright notice and this
permission notice and warranty disclaimer appear in supporting
documentation, and that the name of the author not be used in
advertising or publicity pertaining to distribution of the
software without specific, written prior permission.
The author disclaims all warranties with regard to this
software, including all implied warranties of merchantability
and fitness. In no event shall the author be liable for any
special, indirect or consequential damages or any damages
whatsoever resulting from loss of use, data or profits, whether
in an action of contract, negligence or other tortious action,
arising out of or in connection with the use or performance of
this software.
*/
#include "HD44780.h"
static void HD44780_WriteNibble(const uint8_t nib)
{
/* Read PORTD and clear the ENABLE and PD0..3 bits
then OR in the data */
PORTD = (PORTD & ~(ENABLE | LO4_MASK)) | (nib & LO4_MASK);
/* Enforce address setup time (tAS) 60ns
60 @ 16MHz = <1
Let's us a few NOPs for good measure */
asm volatile("nop\n\t"
"nop\n\t"
:: );
/* Take enable high and enforce Enable High time (tEH=450ns)
450ns @ 16MHz = 7.2 => 7 NOPs */
PORTD |= ENABLE;
asm volatile("nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
:: );
/* Take enable low and enforce Enable Low time (tEL=500ns)
500ns @ 16MHz = 8.0 => 7 NOPs */
PORTD &= ~ENABLE;
asm volatile("nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
"nop\n\t"
:: );
}
static void HD44780_WriteByte(const uint8_t c)
{
HD44780_WriteNibble(HI4(c));
HD44780_WriteNibble(LO4(c));
}
static void HD44780_PowerUp4Bit(void)
{
/* Wait for more than 40 ms after VCC rises to 2.7 V */
_delay_ms(40);
HD44780_WriteNibble(0x03); // FN_SET 8-bit
/* Wait for more than 4.1 ms */
_delay_ms(5);
HD44780_WriteNibble(0x03); // FN_SET 8-bit
/* Wait for more than 100 µs */
_delay_us(100);
HD44780_WriteNibble(0x03); // FN_SET 8-bit
/* From now on we must allow 40us for each command */
_delay_us(50);
HD44780_WriteNibble(0x02); // FN_SET 4-bit
/* The LCD is now in 4-bit mode so we can continue
using the 4-bit API */
_delay_us(50);
}
void HD44780_Initialize(void)
{
PORTD &= ~ALL_BITS;
DDRD |= ALL_BITS;
HD44780_PowerUp4Bit();
}
void HD44780_WriteCommand(const uint8_t c)
{
PORTD &= ~RS;
HD44780_WriteByte(c);
_delay_us(50);
}
void HD44780_WriteData(const uint8_t c)
{
PORTD |= RS;
HD44780_WriteByte(c);
PORTD &= ~RS;
_delay_us(50);
}