If it is set Program Memory is selected and vice versa. When the device is code protected, program or data memory will not be accessible to programmer but CPU may read or write data EEPROM memory.ĮECON1 is the control register used for memory access.ĮEPGD control bit is used to select Program Memory or Data Memory access. The write time is controlled by and on-chip timer and write/erase voltages are generated automatically by an on-chip charge pump. When a data byte is written in to EEPROM, automatically erases the particular location first and then writes the new data (erase before write). Here we deals only with EEPROM data memory.ĮEPROM data memory allows only single byte read and write. EEDATH and EEADRH registers are used when interfacing program memory block with Program Flash Memory. On-Chip charge pump (used while writing data to EEPROM) is turned off when writing these unimplemented locations. On devices having 128 bytes, memory locations from 80h to FFh are unimplemented and will be wraparound to beginning of the data EEPROM memory. PIC Microcontrollers usually have 128/256 bytes of data EEPROM memory with address ranging from 00h to FFh. These memories are not mapped in the register file space, instead of it can be accessed through the following six Special Function Registers (SFR) for read and write operations.ĮEDATA register hold 8-bit data for read/write and EEADR holds the address of EEPROM Memory location to be accessed. The data in the EEPROM and Flash Program Memory can be read/write during normal operations (over full VDD range). Circuit Diagram Simulation of PIC EEPROM using Proteus : In our case for PIC16F877A the available space is 256 bytes as mentioned in its specification datasheet. The amount of storage space available in EEPROM varies upon each microcontroller the details will be given in Datasheet as usual. The data saved in this will be erased only if it is mentioned to do so in the program. As the name suggests it is a memory present inside the PIC Microcontroller in which we can write/read data by programming it to do so. EEPROM stand for “Electronically Erasable and Programmable Read Only Memory”.
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