mirror of
https://github.com/qmk/qmk_firmware.git
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128 lines
3.2 KiB
C
128 lines
3.2 KiB
C
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/*
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LUFA Library
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Copyright (C) Dean Camera, 2017.
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dean [at] fourwalledcubicle [dot] com
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www.lufa-lib.org
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*/
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/*
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Copyright 2017 Dean Camera (dean [at] fourwalledcubicle [dot] com)
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Copyright 2012 Simon Foster (simon.foster [at] inbox [dot] com)
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Permission to use, copy, modify, distribute, and sell this
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software and its documentation for any purpose is hereby granted
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without fee, provided that the above copyright notice appear in
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all copies and that both that the copyright notice and this
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permission notice and warranty disclaimer appear in supporting
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documentation, and that the name of the author not be used in
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advertising or publicity pertaining to distribution of the
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software without specific, written prior permission.
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The author disclaims all warranties with regard to this
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software, including all implied warranties of merchantability
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and fitness. In no event shall the author be liable for any
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special, indirect or consequential damages or any damages
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whatsoever resulting from loss of use, data or profits, whether
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in an action of contract, negligence or other tortious action,
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arising out of or in connection with the use or performance of
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this software.
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*/
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#include "HD44780.h"
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static void HD44780_WriteNibble(const uint8_t nib)
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{
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/* Read PORTD and clear the ENABLE and PD0..3 bits
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then OR in the data */
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PORTD = (PORTD & ~(ENABLE | LO4_MASK)) | (nib & LO4_MASK);
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/* Enforce address setup time (tAS) 60ns
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60 @ 16MHz = <1
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Let's us a few NOPs for good measure */
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asm volatile("nop\n\t"
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"nop\n\t"
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:: );
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/* Take enable high and enforce Enable High time (tEH=450ns)
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450ns @ 16MHz = 7.2 => 7 NOPs */
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PORTD |= ENABLE;
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asm volatile("nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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:: );
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/* Take enable low and enforce Enable Low time (tEL=500ns)
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500ns @ 16MHz = 8.0 => 7 NOPs */
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PORTD &= ~ENABLE;
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asm volatile("nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n\t"
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:: );
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}
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static void HD44780_WriteByte(const uint8_t c)
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{
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HD44780_WriteNibble(HI4(c));
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HD44780_WriteNibble(LO4(c));
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}
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static void HD44780_PowerUp4Bit(void)
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{
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/* Wait for more than 40 ms after VCC rises to 2.7 V */
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_delay_ms(40);
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HD44780_WriteNibble(0x03); // FN_SET 8-bit
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/* Wait for more than 4.1 ms */
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_delay_ms(5);
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HD44780_WriteNibble(0x03); // FN_SET 8-bit
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/* Wait for more than 100 <20>s */
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_delay_us(100);
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HD44780_WriteNibble(0x03); // FN_SET 8-bit
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/* From now on we must allow 40us for each command */
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_delay_us(50);
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HD44780_WriteNibble(0x02); // FN_SET 4-bit
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/* The LCD is now in 4-bit mode so we can continue
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using the 4-bit API */
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_delay_us(50);
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}
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void HD44780_Initialize(void)
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{
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PORTD &= ~ALL_BITS;
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DDRD |= ALL_BITS;
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HD44780_PowerUp4Bit();
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}
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void HD44780_WriteCommand(const uint8_t c)
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{
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PORTD &= ~RS;
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HD44780_WriteByte(c);
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_delay_us(50);
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}
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void HD44780_WriteData(const uint8_t c)
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{
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PORTD |= RS;
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HD44780_WriteByte(c);
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PORTD &= ~RS;
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_delay_us(50);
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}
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