External memory chip for PIC16F877A?

18f4520 external memory

hi guys...

i would like to know what is the suitable external memory chip that can be used with PIC16F877A?

i'm afraid the memory in PIC16F877A won't be enough to implement the Advanced Encryption Standards Algorithms.

Or do i need other PIC for the 18F family to implement the algorithm?

how much ram in pic16f877a

Suggest you consider 18F4520 (32k eeprom, 1.5k ram) or even 18F4620 (64k eeprom, 3.9k ram) if you have a memory-demanding application. These will drive at up to 40 Mhz and also have on-chip multiplication, both of which you might find useful in your application.

Regards

I usually use the 24LC256 (256K bit or 32K byte serial EEPROM). You can use up to 8 memory IC's on the same bus and you can use I2C.

Download the datasheets for more info. You can download it from microchip's site and you can get I2C examples from them.

you can visit microchip's site

Added after 2 minutes:

can you suggest a good pic programming book (prepare downloadable)

Programm memory to enlarge is problem;
External memory you can use only for data, (for exa. more EEPROM bytes for application., not for program)

well thanks for the advices guys.

generally what i'm trying to do for my project is making a portable device that could store a .txt file n make it ureadable by some1 else. To make it unreadable, i'm using the AES encryption algorithm to produce a cipher text(.txt file also).If any 1 else try to access to the information(.txt file) stored in the PIC based hardware, he or she would only be able to read the cipher text file.This cipher text would be unreable to them n only the person who has the secret key used for the algorithm would be able to decrypt the cipher text(.txt file) to produce the original .txt file which is readable.

Of course the hardware i'm using is interfaced to a PC and it works more like a USB mass storage except that its used for security reasons also.

For the 1st phase of my project i need to use an RS-232 serial connection to interface with the PC. Later i would like the upgrade the serial connection to a USB connection.But a lot of people commented that its not easy to use the USB connection for my project.

What is ur views guys?I'm rite now looking into the PIc18F series type of chip to be used for my project. And i guess the use of external memory with PIC16f877a for my project is going make the process of encrypting & decrypting the .txt files slower.

regards

Using external memory will give you more memory than any pic can give you that I know of( 32K Bytes x 8 ). I don't know about the timing differences, but that you'll be able to check it out on the datasheets.

Maybe you should first decide how much memory you need. Then decide on the pic you'll use. Do you really need a 40 pin pic? Does your programming language support the pic you want?