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Diffstat (limited to 'Projects/SerialToLCD/Lib/HD44780.c')
| -rw-r--r-- | Projects/SerialToLCD/Lib/HD44780.c | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/Projects/SerialToLCD/Lib/HD44780.c b/Projects/SerialToLCD/Lib/HD44780.c new file mode 100644 index 000000000..d67dc6d40 --- /dev/null +++ b/Projects/SerialToLCD/Lib/HD44780.c @@ -0,0 +1,127 @@ +/* + LUFA Library + Copyright (C) Dean Camera, 2012. + + dean [at] fourwalledcubicle [dot] com + www.lufa-lib.org +*/ + +/* + Copyright 2012 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 disclaim 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_Initialise(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); +} |