Microchip Technology MA240017 Data Sheet

DS39927C-page 56

 2008-2011 Microchip Technology Inc.

6.4.3

READING THE DATA EEPROM

To read a word from data EEPROM, the table read
instruction is used. Since the EEPROM array is only
16 bits wide, only the TBLRDL instruction is needed.
The read operation is performed by loading TBLPAG
and WREG with the address of the EEPROM location,
followed by a TBLRDL instruction.

A typical read sequence, using the Table Pointer manage-
ment (builtin_tblpage and builtin_tbloffset)
and table read (builtin_tblrdl) procedures from the
C30 compiler library, is provided in 

Program Space Visibility (PSV) can also be used to
read locations in the data EEPROM.

int __attribute__ ((space(eedata))) eeData = 0x1234;

// Variable located in EEPROM,declared 

// as a global variable

int data;                // Data read from EEPROM

unsigned int offset;

// Set up a pointer to the EEPROM location to be erased

TBLPAG = __builtin_tblpage(&eeData);

// Initialize EE Data page pointer

offset = __builtin_tbloffset(&eeData);

// Initizlize lower word of address

data   = __builtin_tblrdl(offset);

// Write EEPROM data to write latch