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2001 Microchip Technology Inc. DS39024B-page 53
LCD.C Description
/
*******************************************************************
*
* Function Name: ReadDataXLCD
* Return Value: char: data byte from LCD controller
* Parameters: void
* Description: This routine reads a data byte from the
* Hitachi HD44780 LCD controller. The user
* must check to see if the LCD controller is
* busy before calling this routine. The data
* is read from the character generator RAM or
* the display data RAM depending on what the
* previous SetxxRamAddr routine was called.
*******************************************************************
*/
char ReadDataXLCD(void)
{
char data;
#ifdef BIT8 // 8-bit interface
RS_PIN = 1; // Set the control
bits
RW_PIN = 1;
DelayFor18TCY();
E_PIN = 1; // Clock the data out
of the LCD
DelayFor18TCY();
data = DATA_PORT; // Read the data
E_PIN = 0;
RS_PIN = 0; // Reset the control
bits
RW_PIN = 0;
#else // 4-bit interface
RW_PIN = 1;
RS_PIN = 1;
DelayFor18TCY();
E_PIN = 1; // Clock the data out
of the LCD
DelayFor18TCY();
#ifdef UPPER // Upper nibble
interface
data = DATA_PORT&0xf0; // Read the upper
nibble of data
#else // Lower nibble
interface
data = (DATA_PORT<<4)&0xf0; // read the upper
nibble of data
#endif
E_PIN = 0; // Reset the clock
line
DelayFor18TCY();
E_PIN = 1; // Clock the next
nibble out of the LCD
DelayFor18TCY();
#ifdef UPPER // Upper nibble
interface
data |= (DATA_PORT>>4)&0x0f; // Read the lower
nibble of data