Hi Mohit,

From what you've said it sounds like the unknown variable is the size of you
code.
If you have access to a C compiler then I'd suggest making a start on the
program to get a feel for how much space you'll need, you might be pleasantly
surprised.

If you do exceed 8K then a least you'll know more accurately what your
requirements are. Have you looked at the PIC17C756 & 766? They're not Flash but
they would give you 16K to play with and they're available now.

I have no experience of using EEPROM to hold program code but it sounds messy.

Good luck.

Nigel


On Friday, February 22, 2002 12:09 PM, Mohit Mahajan [SMTP:m0h1t@YAHOO.CO.IN]
wrote:
> Hi,
>
> I'm new to PIC. I am planning to implement a control system using PIC16F877.
> I'll be using a keypad, LCD, almost all I/O pins (to input the control
> variables, operate four switches, PWM etc.).
>
> The code for all this is going to be large, no doubt. A PIC expert could
> optimise it to fit in the 8K ROM of the PIC, but as I'm a novice I'm not
> sure I'll be able to do so. In any case, since I'll either use JAL or a
> C-compiler, the code will be more than 8K. So now my question is:
>
> Can we interface an EEPROM [specifically: 24LC256, 32Kbyte Flash EEPROM
> (I2C)] to the PIC in such a way that the firmware code can be written in the
> EEPROM, from where the PIC can fetch it in packets and run it?
>
> It doesn't matter to my application if the effective operating speed
> decreases, because I'll be controlling pH, temperature, dissolved oxygen
> (all these take few minutes to adjust).
>
> If no, and the firmware is greater than 8K, then what should I do? Is there
> anything available with Microchip that has a larger (flash) ROM and as many
> I/O as the PIC 16F877? I've read about PIC18F242, but it still isn't out in
> the market.
>
> Peace,
> Mohit Mahajan.
>
>
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