Can you use a pi as an eeprom emulator?

If you refer to the datasheet, the first line reads: "Fast acces time: 150ns". This means that anywhere that when emulating you  have a 150ns time window to react to the inputs of the circuit where the chip is being emulated.

Using "bare metal" programming I'd say that would be "worth a try". But keepnig convenient things like Linux running on the 'pi would be impossible.

That said: you're going to emulate a 28-pin chip. With only two power pins you'll need 26 free GPIO pins. I don't think the 'pi has that many free GPIOs.

I agree with Roger, the PI would not be the best

What I did "Years.... ago" was to create a static ram version of the eprom with a batery backup to keep the contents

This way you can load the ram quickly and as often as you want and then use it in the target system, no waiting for erasure cycles or slow programing

It is easy to get static ram chips that are as fast as the eeproms your using

Just an idea, hope it helps

Peter

i am very new to all this so could you provide a link or something to help me out also could i use something other than the pi like an arduino or cheap fpga

If I needed one I would build it myself  - either on a custom pcb or possibly on veroboard wired point to point with solderable wire (I don't use that technique much now.)

I was going to suggest a little FPGA baord from lattice but it won't be 5V compatible.

Are you able to make a board or wire on veroboard  -the chips won't cost much, Farnell have a 512k x 8 (4Mbit RAM) in DIP and 5V tolerant for £3.31 - you'll need a handful of other chips but it isn't a huge job.

MK

i dont really have any experience with this im new, i am looking to make or setup the simplest and/or cheapest eprom/eeprom emulator for M27C256B and AT28C256 chips i just need to know where to start or what to buy

Hi Michael,

Since you mention simplest/cheapest, a quick solution is to use a software simulator or emulator. A lot of the old games consoles have emulators that run on a PC. It may be quicker to prototype directly in such an emulation/simulation and then write to EEPROM (or EPROM) when you've ironed out all bugs.

As a digression, I once had up to 50 attempts to develop some software for a particular offering - because I only had 50 OTP devices (no EPROM windows : ).

The software was complete and product delivered to a customer within just a dozen attempts. Partially this was due to testing on a PC as much as possible.

yeah i know i could do that but im looking for a simple hardware solution as a bit of a project to do but thank you for the suggestion

Something like this is what you may be looking for

8-Bit EPROM/SRAM Emulator

Peter

You can make a fifo or lifo by attaching a counter to the address lines of a SRAM.

You can dual-port it by using '244s, '245s and a little bit of glue logic.

With two SRAMs you can set up a dual-port ping-pong.  Say 'master/slave' to your GF with a straight face!

You can back it up on power-down with a coupla button cells and a low-drop diode.

Of course, the host doesn't have to be anywhere near as fast as the SRAM.

The link to the zip file seems to be broken - otherwise it looks like the sort of thing the OP needs but if he can't build it himself he's going to have to pay for one.

Most of the ones I found on the web are no longer in production:

Here is a nice one:

http://www.batronix.com/shop/epromemulator/emulator.html?gclid=Cj0KEQjw_rytBRDVhZeQrbzn_q0BEiQAjnbSHOPhzqIJKTTlTS_n50vVxQARIFnY0MN0oErN2SmsxAUaAt-j8P8HAQ

But very pricey compared with the £20 I guess it would cost to home build one.

MK