How to select 16-bit or 8-bit mode on flash Eprom chip like S29GL064

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Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

How to select 16-bit or 8-bit mode on flash Eprom chip like S29GL064

Post by Kayumba »

Hi again,
I would like to do PCB repro version with flash eprom 3v.
I make my chose with S29GL064 to do my first try.
Reading datasheet I see that it can be use like 16-bit data bus and 8-bit also.
So that’s great cause no need to use multiplexers between chip and SNES.

To select what mode I want to use, I have to use pin named « BYTE# » .
But how to select between 16-bit or 8-bit mode ?
Its says that « if the BYTE# pin is set to logic « 0 » the device is in byte configuration.
But for what mode I don’t understand?
Don’t understand when it’s configured to 8-bit.

Can you help please.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: How to select 16-bit or 8-bit mode on flash Eprom chip like S29GL064

Post by lidnariq »

A byte is 8 bits.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: How to select 16-bit or 8-bit mode on flash Eprom chip like S29GL064

Post by Kayumba »

lidnariq wrote: Sun Apr 25, 2021 1:37 pm A byte is 8 bits.
Thanks 🙏
So,
Set BYTE# pin to logic « 0 » (GND) makes configure in 8-bit mode, is that exact ?
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: How to select 16-bit or 8-bit mode on flash Eprom chip like S29GL064

Post by lidnariq »

Yes.

Note that the absence of the multiplexers aren't an unambiguous win, because those external multiplexers can provide the needed voltage-translation to protect the SNES and ROM from each other.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: How to select 16-bit or 8-bit mode on flash Eprom chip like S29GL064

Post by Kayumba »

lidnariq wrote: Sun Apr 25, 2021 2:17 pm Yes.

Note that the absence of the multiplexers aren't an unambiguous win, because those external multiplexers can provide the needed voltage-translation to protect the SNES and ROM from each other.
Thank you.
About « voltage - translation » i know.

Not sure about if « RESET » , « CE », « OE » and « WE » signals have to be translated too.
Suppose that all depends of chip voltage supply .
I mean if signals are communicating between SNES and chip, so it’s have to be « translated »

Something about 34 pins to « translate » , OMG!

Have no idea if SRAM decoder like « 74*139 », if it’s accepting 3v signals...?
Or if its better to use 5v signals for 74*139 ?
Last edited by Kayumba on Sun Apr 25, 2021 3:35 pm, edited 1 time in total.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: How to select 16-bit or 8-bit mode on flash Eprom chip like S29GL064

Post by lidnariq »

Yup, everything.

Certain 74xxx parts are 5V tolerant when powered by 3.3V, so you may not need explicit down-translation for them.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: How to select 16-bit or 8-bit mode on flash Eprom chip like S29GL064

Post by Kayumba »

lidnariq wrote: Sun Apr 25, 2021 3:34 pm Yup, everything.

Certain 74xxx parts are 5V tolerant when powered by 3.3V, so you may not need explicit down-translation for them.
Thanks again for your help lidnariq !
Wish you long and healthy life 💪🏼
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