Is there anyway the prop can read from a non i2c eprom?

djh82uk

Heya

Jut a quick question, is it possible to read from an old otp eprom with the prop? How difficult would it be (im presuming difficult)?

The chips is a: 27C160

Datasheet here:
http://www.datasheet4u.com/download.php?id=489562

Thanks in advance

DJH

Paul Baker

If you are using an already programmed 27C160, you could interface it to the prop by observing the required resistors on the datalines since it is a 5V part. Used in byte-wide mode and straight connection, it would consume all off the propeller's I/O pins (remember the prop will need 4 I/O at least during development).

If your question is if the Propeller is capable of booting it's program from the 27C160 at startup, the answer is no it can not.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

djh82uk

I was more hoping I could just read the contents of one via prop and maybe dump it to SD card, but I guess with no I/O pins left it could not do much anyway?

DJH

Paul Baker

No it's possible, all you need is some latches and use them to hold some data. With a couple of 8 bit latches you could use them to supply A0-A15, so 8 bits for the data lines, 8 bits for address, then a couple control pins to indicate which part of the address you are updating, so roughly 18 I/O. With the 4 I/O for I2C EEPROM and PC link, that leaves 10 I/O, more than enough to attach an SD card.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

djh82uk

Im still pretty new to all this so I will have to look into latches and example circuits I guess.

Basically I was hoping to be able to dump the eeprom to the SD card via a very simply menu outputed to TV. But then I forgot the need to have buttons etc to be able to select options, Or I guess I could have 2 props? One to handle Eeprom/SD and one to handle input buttons, and TV out, that way all the tv out prop would need to send (via serial?) is what option was chosen and any arguments that go with it.

Id love to try and do this but I think It will take me a while to figure out the circuit, let alone the code.

Perhaps I will start with the TV menu and controller interface first.

Thanks for all your help, any other tips?

DJH

deSilva

As you seem to have no need for fast direct access think of connecting a counter - e.g. some version of a CD4040 (or two cascaded) - to the address lines. You can easily step through a MB in one sec with just a single line (or two)

RinksCustoms

if you like i could whip something up in MULTISIM (one of the high-end schematic capture/spice sims) and post/e-mail you the shematic..

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Definetly a E³ (Electronics Engineer Extrodinare!)
"I laugh in the face of imposible,... not because i know it all, ... but because I don't know well enough!"

djh82uk

Yes if you could email some info it would be greatly appreciated.

Would there also be a way to write to another eeprom? The only thing I can't figure out, there is obviously no way to "replay" the contents of the sd card as if it came from the original eeprom is there? Other systems in the past have written it to a floppy drive and replayed from there but they used a custom asic which is obviously way beyond my scope.

what I would like to do in the long run is read from an eeprom in situ, save it somewhere, and be able to play it back on the same system without the original eeprom being there. But I would like it to be some form of removable media so that it can be played back on another identical system. Each system has different contents on their eeprom. Im not looking to rush this, and I am happy to take baby steps, and Iam going to play with a few other much easier projects first, but would like to play with this when I get chance.

If any of that makes sense?