HOW I EXTEND THE MEMORY OF THE PIC IF CODE IS LARGE

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Fragrance

Joined: 26 Jul 2002
Posts: 1385
Helped: 24

18 Jun 2003 15:00 HOW I EXTEND THE MEMORY OF THE PIC IF CODE IS LARGE

HI FRIENDS

I need your help regarding this post i am using a pic16f877 my application
required a complex code so memory is problem how i extend the memory of the chip
because i want to use only this chip in my design

regards
Fragrance

C-Man

Joined: 19 Jul 2001
Posts: 1235
Helped: 73

18 Jun 2003 15:12

I am afraid you can not extend the code memory of a PIC 16F877.

You could for example if you have lots of strings in your program put these strings in an external eeprom which can be acessed via I2C or SPI bus. You would have to get the string whenever it is required from external EEPROM. I have no idea if your application allows this.

Another method (which I use often) is to use a PIC 18F452 (which has twice the code capacity) instead of the 16F877 it is pin compatible and if your software is written in C all you have to do is to recompile with a compiler for the PIC 18 series.

hope this helps

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carrotts

Joined: 31 Jan 2002
Posts: 40

18 Jun 2003 15:45

Fragrance

The 18f PICs are comparable on price, and much more powerful. If you are using PIC basic, you need to change a few settings at the start, and you're away. Got a listing using an 18f somewhere, will dig the setting changes out if you need them.

Regards

Carrotts

nebisman

Joined: 13 Apr 2002
Posts: 291
Helped: 1

18 Jun 2003 17:20

I undesrtood that 18F series allows external memory like intel MCU, the datasheet tell about 2MB linear code adressing. How is this?

btbass

Joined: 20 Jul 2001
Posts: 1187
Helped: 113
Location: Oberon

18 Jun 2003 19:09

One possible way, (untried), would be to use an external i2c eeprom, available up to 64K from microchip, the pic16f877 can program its own code space, so you could use a pageing system, load in code blocks as they are needed, program them, then run them. Might work if speed is not a problem?