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readaddr.c
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readaddr.c
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#include <p18cxxx.h>
#include <xlcd.h>
/*********************************************************************
* Function Name: ReadAddrXLCD *
* Return Value: char: address from LCD controller *
* Parameters: void *
* Description: This routine reads an address byte from the *
* Hitachi HD44780 LCD controller. The user *
* must check to see if the LCD controller is *
* busy before calling this routine. The address*
* is read from the character generator RAM or *
* the display data RAM depending on what the *
* previous SetxxRamAddr routine was called. *
*********************************************************************/
unsigned char ReadAddrXLCD(void)
{
char data; // Holds the data retrieved from the LCD
#ifdef BIT8 // 8-bit interface
RW_PIN = 1; // Set control bits for the read
RS_PIN = 0;
DelayFor18TCY();
E_PIN = 1; // Clock data out of the LCD controller
DelayFor18TCY();
data = DATA_PORT; // Save the data in the register
E_PIN = 0;
RW_PIN = 0; // Reset the control bits
#else // 4-bit interface
RW_PIN = 1; // Set control bits for the read
RS_PIN = 0;
DelayFor18TCY();
E_PIN = 1; // Clock data out of the LCD controller
DelayFor18TCY();
#ifdef UPPER // Upper nibble interface
data = DATA_PORT&0xf0; // Read the nibble into the upper nibble of data
#else // Lower nibble interface
data = (DATA_PORT<<4)&0xf0; // Read the nibble into the upper nibble of data
#endif
E_PIN = 0; // Reset the clock
DelayFor18TCY();
E_PIN = 1; // Clock out the lower nibble
DelayFor18TCY();
#ifdef UPPER // Upper nibble interface
data |= (DATA_PORT>>4)&0x0f; // Read the nibble into the lower nibble of data
#else // Lower nibble interface
data |= DATA_PORT&0x0f; // Read the nibble into the lower nibble of data
#endif
E_PIN = 0;
RW_PIN = 0; // Reset the control lines
#endif
return (data&0x7f); // Return the address, Mask off the busy bit
}