gistfile1.txt

a

hd44780.h

#pragma once

// {{{ various HD44780 opcodes:
#define HD44780_CLEAR				0b00000001
#define HD44780_RET_HOME			0b00000010
#define HD44780_ENTRY_MODE			0b00000100
#define  HD44780_EM_SHIFT			0b00000001
#define  HD44780_EM_INC				0b00000010
#define  HD44780_EM_LEFT			0b00000010
#define  HD44780_EM_DEC				0b00000000
#define  HD44780_EM_RIGHT			0b00000000
#define HD44780_DISP				0b00001000
#define  HD44780_DISP_DISP_ON		0b00000100
#define  HD44780_DISP_DISP_OFF		0b00000000
#define  HD44780_DISP_CURSOR_ON		0b00000010
#define  HD44780_DISP_CURSOR_OFF	0b00000000
#define  HD44780_DISP_BLINK_ON		0b00000001
#define  HD44780_DISP_BLINK_OFF		0b00000000
#define HD44780_DISP_SHIFT			0b00010000
#define	HD44780_SET					0b00100000
#define	 HD44780_SET_8_BIT			0b00010000
#define	 HD44780_SET_4_BIT			0b00000000
#define	 HD44780_SET_2_LINE			0b00001000
#define	 HD44780_SET_1_LINE			0b00000000
#define	 HD44780_SET_5x10_FONT		0b00000100
#define	 HD44780_SET_5x8_FONT		0b00000000
#define HD44780_SET_CGRAM			0b01000000
#define HD44780_SET_DDRAM			0b10000000
// }}}

#ifdef __AVR__

#define PORT_TO_DDR(port) (*(&port - 1))

#define HD44780_EN_PORT	PORTB
#define HD44780_EN_BIT	5
#define HD44780_EN_DDR	PORT_TO_DDR(HD44780_EN_PORT)

#define HD44780_RS_PORT	PORTD
#define HD44780_RS_BIT	6
#define HD44780_RS_DDR	PORT_TO_DDR(HD44780_RS_PORT)

#define HD44780_RW_PORT	PORTB
#define HD44780_RW_BIT	4
#define HD44780_RW_DDR	PORT_TO_DDR(HD44780_RW_PORT)

#define HD44780_D0_PORT	PORTB
#define HD44780_D0_BIT	0
#define HD44780_D0_DDR	PORT_TO_DDR(HD44780_D0_PORT)

#define HD44780_D1_PORT	PORTB
#define HD44780_D1_BIT	1
#define HD44780_D1_DDR	PORT_TO_DDR(HD44780_D1_PORT)

#define HD44780_D2_PORT	PORTB
#define HD44780_D2_BIT	2
#define HD44780_D2_DDR	PORT_TO_DDR(HD44780_D2_PORT)

#define HD44780_D3_PORT	PORTB
#define HD44780_D3_BIT	3
#define HD44780_D3_DDR	PORT_TO_DDR(HD44780_D3_PORT)

#define bit_check_and_set(dbyte, dbit, port, pbit)\
	asm volatile ("sbrs	%0, %1\n\t"	:: "r" (dbyte), "I"(dbit));\
	asm volatile (" cbi	%0, %1\n\t" :: "I" (_SFR_IO_ADDR(port)), "I"(pbit));\
	asm volatile ("sbrc	%0, %1\n\t" :: "r" (dbyte), "I"(dbit));\
	asm volatile (" sbi	%0, %1\n\t" :: "I" (_SFR_IO_ADDR(port)), "I"(pbit))

void HD44780_W4B (const byte b) asm ("HD44780_W4B") __attribute__((used));
void HD44780_W4B (const byte b)
{
	sbi (HD44780_EN_PORT, HD44780_EN_BIT);

	// this provides the necesary delay: (atleast 44 cycles ~= 3us)	
	bit_check_and_set (b, 0, HD44780_D0_PORT, HD44780_D0_BIT);
	bit_check_and_set (b, 1, HD44780_D1_PORT, HD44780_D1_BIT);
	bit_check_and_set (b, 2, HD44780_D2_PORT, HD44780_D2_BIT);
	bit_check_and_set (b, 3, HD44780_D3_PORT, HD44780_D3_BIT);
	nop();
	cbi (HD44780_EN_PORT, HD44780_EN_BIT);
}

#define FAST
//static void HD44780_W8B (byte value) __attribute__((used(HD44780_W4B)));
static void HD44780_W8B (byte value)
{
	#ifdef FAST
	asm volatile("swap %0			\n\t" : "=r" (value) : "0" (value));
	asm volatile("rcall HD44780_W4B	\n\t");
	asm volatile("swap %0			\n\t" : "=r" (value) : "0" (value));
	asm volatile("rcall HD44780_W4B	\n\t");
	#else
	HD44780_W4B(value >> 4);
	HD44780_W4B(value);
	#endif
	
	_delay_ms (2);
}

static void HD44780_init()
{
	// Setup DDRS
	sbi (HD44780_EN_DDR, HD44780_EN_BIT);
	sbi (HD44780_RS_DDR, HD44780_RS_BIT);
	sbi (HD44780_RW_DDR, HD44780_RW_BIT);

	sbi (HD44780_D0_DDR, HD44780_D0_BIT);
	sbi (HD44780_D1_DDR, HD44780_D1_BIT);
	sbi (HD44780_D2_DDR, HD44780_D2_BIT);
	sbi (HD44780_D3_DDR, HD44780_D3_BIT);
	// MPU-controlled init (hd44780.pdf page 46):
// init state = 0
//	cbi (HD44780_RS_PORT, HD44780_RS_BIT);
//	cbi (HD44780_RW_PORT, HD44780_RW_BIT);
//	cbi (HD44780_EN_PORT, HD44780_EN_BIT);

//	_delay_ms(100); // unneeded? see SUT?
//#define INIT
#ifdef INIT
	// Set 8bit mode - lolinit
	HD44780_W4B (0b0011);
	_delay_ms (5);

	HD44780_W4B (0b0011);
	_delay_ms (5);

	HD44780_W4B (0b0011);
	_delay_ms (5);

#endif
	// Set 4bit mode
	HD44780_W4B (0b0010);

	_delay_ms (5);

	HD44780_W8B (	HD44780_SET
		|	HD44780_SET_4_BIT
		|	HD44780_SET_2_LINE
		|	HD44780_SET_5x8_FONT);

	HD44780_W8B (	HD44780_DISP
		|	HD44780_DISP_DISP_ON
		|	HD44780_DISP_CURSOR_ON
		|	HD44780_DISP_BLINK_ON);
			
	HD44780_W8B (	HD44780_CLEAR);

	HD44780_W8B (	HD44780_ENTRY_MODE
		|	HD44780_EM_INC);

	// Write H
}
#endif