Anyone has written a driver for the AM29F040 flash ?

proton · Joined: 10 Dec 2005 Posts: 3

Hi friends,
I need to interface a flash chip AM29F040 to a 18F8621.
Does someone has written a driver or has a piece of code that
I could take as example ?
thanks a lot

proton

Ttelmah · Guest

Seriously, this is a parallel memory, so you need 30 I/O lines. Few older PIC's can provide this many general purpose connections while still leaving any pins for anything else.
Most of the drivers around are for the much more complex job of handling serial memories, but with the big advantage of using less lines.
Do you really have to use a chip with this many connections?. Which processor do you intend to use?. Which ports do you want to use?.
If ports/pins are going to be short, then you may need to consider something like an external addressable 'latch' for the addresses, which would allow the interface to be generated, with perhaps 15 lines.
The actual control of the chip is not hard, but there are a couple of 'erratas' that apply to older releases. A lot is going to depend what you actually want to 'do' with the chip. Just reading it is easy. Writing, provided the data is being transmitted from another device is also easy. If however you want the PIC to do anything 'intelligent', in terms of modifying the data on the chip, you will have problems, since with it's 64K sector size, you are going to need a second memory, large enough to hold an entire sector, if you want to 'set' any bits ithe array (the array clears to '1', and you can program individual bytes to '0', but to change a byte back to '1', you have to read the entire sector, perform a block erase, and then write the whole sector back.

Best Wishes

proton · Joined: 10 Dec 2005 Posts: 3

yes, that's all true. But unfortunately the request come directly
from the customer ... besides I was not able to find any serial 4 Mbit
chip.
Any idea ?
So the driver for the AM29F040 would be very appreciated ...
proton

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

I have a driver for the AM29F040 that runs on a PC. It was written for
a MSVC 16-bit C compiler, several years ago. I wrote it to make my
own prom programmer for that chip, that runs on a board for the ISA
bus. If you understand how a 16-bit DOS program works on a PC,
and if you understand the difference between MSVC vs. 1.52 and the
CCS compiler (particularly with respect to data types) then you could
convert it to CCS. I don't really want to support it. Given all that,
do you want me to PM you the driver source file ?

proton · Joined: 10 Dec 2005 Posts: 3

Hi,
yes I'd like to look at it ... eventually I will not use the code
and restart from scratch ...
please PM me ...
thanks
proton