/*
* description: clear the display on the LCD
*/
static void lcd_clearDisplay()
{
lcd_instruction( 0x00 ); // upper 4 bits of command
lcd_instruction( 0x10 ); // lower 4 bits of command
printk(KERN_INFO "klcd Driver: display clear\n");
}
/*
* description: turn off the LCD display. It is called upon module exit
*/
static void lcd_display_off(void)
{
lcd_instruction(0x00); // Instruction 0000b
lcd_instruction(0x80); /* Instruction 1DCBb
Set D= 0, or Display off
Set C= 0, or Cursor off
Set B= 0, or Blinking off
*/
printk(KERN_INFO "klcd Driver: lcd_display_off\n");
}
/*
* description: hide a blinking cursor from the LCD screen
*/
static void lcd_cursor_off()
{
/* Display On/off Control */
lcd_instruction(0x00); // Instruction 0000b
lcd_instruction(0xC0); /* Instruction 1DCBb
Set D= 1, or Display on
Set C= 0, or Cursor off
Set B= 0, or Blinking off
*/
printk(KERN_INFO "klcd Driver: lcd_cursor_off\n");
}
// Reset, as per page 34 of 7920 data sheet
void lcd_reset() {
// Bring (PB0) low, then high
PORTB &= ~0x01;
_delay_ms(1);
PORTB |= 0x01;
_delay_ms(10);
lcd_instruction(0b00110000); // 8 bit data, basic instructions
lcd_instruction(0b00110000); // 8 bit data, basic instructions
lcd_instruction(0b00001100); // d_buffer on
lcd_clear();
lcd_instruction(0b00000110); // increment, no shift
}
/*
* description: set the cursor to the beginning of the line specified.
* @param line line number should be either 1 or 2.
*/
void lcd_setLinePosition(unsigned int line)
{
if(line == 1) {
lcd_instruction(0x80); // set position to LCD line 1
lcd_instruction(0x00);
}
else if(line == 2) {
lcd_instruction(0xC0);
lcd_instruction(0x00);
}
else {
printk("ERR: Invalid line number. Select either 1 or 2 \n");
}
}
/*
* description: set the cursor to the nth character of the line specified.
* @param line the line number should be either 1 or 2.
* @param nthCharacter n'th character where the cursor should start on the line specified.
* It starts from 0, which indicates the beginning of the line.
*/
void lcd_setPosition(unsigned int line, unsigned int nthCharacter)
{
char command;
if(line == 1) {
command = 0x80 + (char) nthCharacter;
lcd_instruction( command & 0xF0 ); // upper 4 bits of command
lcd_instruction( (command & 0x0F) << 4 ); // lower 4 bits of command
}
else if(line == 2) {
command = 0xC0 + (char) nthCharacter;
lcd_instruction( command & 0xF0 ); // upper 4 bits of command
lcd_instruction( (command & 0x0F) << 4 ); // lower 4 bits of command
}
else {
printk("ERR: Invalid line number. Select either 1 or 2 \n");
}
}
/*
* description: initialize the LCD in 4 bit mode as described on the HD44780 LCD controller document.
*/
static void lcd_initialize()
{
usleep_range(41*1000, 50*1000); // wait for more than 40 ms once the power is on
lcd_instruction(0x30); // Instruction 0011b (Function set)
usleep_range(5*1000, 6*1000); // wait for more than 4.1 ms
lcd_instruction(0x30); // Instruction 0011b (Function set)
usleep_range(100,200); // wait for more than 100 us
lcd_instruction(0x30); // Instruction 0011b (Function set)
usleep_range(100,200); // wait for more than 100 us
lcd_instruction(0x20); /* Instruction 0010b (Function set)
Set interface to be 4 bits long
*/
usleep_range(100,200); // wait for more than 100 us
lcd_instruction(0x20); // Instruction 0010b (Function set)
lcd_instruction(0x80); /* Instruction NF**b
Set N = 1, or 2-line display
Set F = 0, or 5x8 dot character font
*/
usleep_range(41*1000,50*1000);
/* Display off */
lcd_instruction(0x00); // Instruction 0000b
lcd_instruction(0x80); // Instruction 1000b
usleep_range(100,200);
/* Display clear */
lcd_instruction(0x00); // Instruction 0000b
lcd_instruction(0x10); // Instruction 0001b
usleep_range(100,200);
/* Entry mode set */
lcd_instruction(0x00); // Instruction 0000b
lcd_instruction(0x60); /* Instruction 01(I/D)Sb -> 0110b
Set I/D = 1, or increment or decrement DDRAM address by 1
Set S = 0, or no display shift
*/
usleep_range(100,200);
/* Initialization Completed, but set up default LCD setting here */
/* Display On/off Control */
lcd_instruction(0x00); // Instruction 0000b
lcd_instruction(0xF0); /* Instruction 1DCBb
Set D= 1, or Display on
Set C= 1, or Cursor on
Set B= 1, or Blinking on
*/
usleep_range(100,200);
}
// Clears the text screen
void lcd_clear() {
lcd_instruction(0b00000001); // clear
_delay_ms(2); // Needs 1.62ms delay
}
void lcd_signed(unsigned char line, signed int value, char digits)
{
lcd_instruction(line);
lcd_print(value, 10, SIGNED_ZEROS, digits);
}
void lcd_hexidecimal(unsigned char line, unsigned int value, char digits)
{
lcd_instruction(line);
lcd_print(value, 16, UNSIGNED_ZEROS, digits);
}
void lcd_binary(unsigned char line, unsigned int value, char digits)
{
lcd_instruction(line);
lcd_print(value, 2, UNSIGNED_ZEROS, digits);
}
