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Pic Programming

EEPROM Data Memory

PIC16f84 has 64 by tes of EEPROM memory locations on addresses from OOh to 63h those can be written to or read from. The most im porta nt characteristic of this memory is that it does not loose its contents during power supply turned off. That practically means that what was written to it will be remaining eve n if microcontroller is turned off. Data can be retained in EEPROM without power supply for up to 40 years (as manufacturer of PIC16f84 microcontroller states), and up to 10000 cycles of writing can be executed.
 

In practice, EEPROM memory is used for storing important data or some process parameters. One such parameter is a given temperature, assigned when setting up a temperature regulator to some process. if that data wasn´t retained, it would be necessary to adjust a given temperature after each loss of supply. Since this is very impractical (and eve n dangerous), manufacturers of microcontrollers have began installing one smailer type of EEPROM memory.
EEPROM memory is placed in a special memory space and can be accessed through special registers. These registers are:
 

. EEDATA at address 08h, which holds read data or that to be written.
. EEADR at address 09h, which contains an address of EEPROM l o c a t i o n. being accessed.
. EECONı at address 88h, which contains control bits.
. EECON2 at address 89h. This register does not exist physically and serves to protect EEPROM from accidental writing.
 


Keywords : EEPROM, Data, Memory, Pic, Programming, Assembly, Assembler, Mplab, EEDATA, EEADR
Writer : delon  |
3 Mar 2006 Fri   
|  4.262 Views
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