AVR-Chat

--- In AVR-Chat@yahoogroups.com, "Arif YILMAZ" <arif.yilmaz@b...> wrote:
> hello  dear members,
> i need a high capacity serial flash chip and i will use the following
> from ST ,
>  
> http://www.st.com/stonline/products/literature/ds/10980/m25pe40.htm
>  
>  but it is 3.3 V
>  
> do you know any other alternative for this serial flash memory about
> 512K flash with SPI interface and 5V supply?

Hi Arif,

I'm using the dataflashs from Atmel in some applications. They're 3.3V 
too, but fully 5V-tolerant at the I/Os. A small LDO like 
LP2950/2980/2985 for the 3.3V and you're done...

Stefan

Stefan,
When you say '5V tolerant' I understand that a micro (@5V) can write to the 
Flash (@3.3v).
But what do you do for the data coming OUT of the data flash?  So you just 
use a pull-up resistor, or something else?

Ivan.
----- Original Message ----- 

From: "Stefan Wimmer" <yahoo@wsw-elektronik.de>
To: <AVR-Chat@yahoogroups.com>
Sent: Thursday, September 01, 2005 2:51 AM
Subject: [AVR-Chat] Re: Serial Flash


> --- In AVR-Chat@yahoogroups.com, "Arif YILMAZ" <arif.yilmaz@b...> wrote:
>> hello  dear members,
>> i need a high capacity serial flash chip and i will use the following
>> from ST ,
>>
>> http://www.st.com/stonline/products/literature/ds/10980/m25pe40.htm
>>
>>  but it is 3.3 V
>>
>> do you know any other alternative for this serial flash memory about
>> 512K flash with SPI interface and 5V supply?
>
> Hi Arif,
>
> I'm using the dataflashs from Atmel in some applications. They're 3.3V
> too, but fully 5V-tolerant at the I/Os. A small LDO like
> LP2950/2980/2985 for the 3.3V and you're done...
>
> Stefan
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>

Hi Stefan, 
I couldn't have a look at the chips at atmel (atmel pdfs just don't show
up on my browser)  but as far as I know  they are not 8 pin devices, but
they are cool as well I will consider thank you.

And Hi Ivan, most microcontrollers today have schmitt triggered inputs
and they accept about 1.5V and above as high level ( values may be
changing) 
 so 3.3 V flash data output is enough to capture high value, 
For dataflash inputs, putting a 5K resistor between micro's output pin
and flash input pin is enough (5-3.3)/1k supplies  ~0.3mA  and it does
not destroy flashinput pin (which normally has a high impedance and
doesn't draw any current  at all till above 3.3V) 
Above 3.3 V input protection diodes of the flash will keep voltage at
3.3 level.

-----Original Message-----
From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On
Behalf Of Ivan Vernot
Sent: Thursday, September 01, 2005 2:40 AM
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] Re: Serial Flash


Stefan,
When you say '5V tolerant' I understand that a micro (@5V) can write to
the 
Flash (@3.3v).
But what do you do for the data coming OUT of the data flash?  So you
just 
use a pull-up resistor, or something else?

Ivan.
----- Original Message ----- 
From: "Stefan Wimmer" <yahoo@wsw-elektronik.de>
To: <AVR-Chat@yahoogroups.com>
Sent: Thursday, September 01, 2005 2:51 AM
Subject: [AVR-Chat] Re: Serial Flash


> --- In AVR-Chat@yahoogroups.com, "Arif YILMAZ" <arif.yilmaz@b...> 
> wrote:
>> hello  dear members,
>> i need a high capacity serial flash chip and i will use the following

>> from ST ,
>>
>> http://www.st.com/stonline/products/literature/ds/10980/m25pe40.htm
>>
>>  but it is 3.3 V
>>
>> do you know any other alternative for this serial flash memory about 
>> 512K flash with SPI interface and 5V supply?
>
> Hi Arif,
>
> I'm using the dataflashs from Atmel in some applications. They're 3.3V

> too, but fully 5V-tolerant at the I/Os. A small LDO like 
> LP2950/2980/2985 for the 3.3V and you're done...
>
> Stefan
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
> 




 
Yahoo! Groups Links

On Fri, 2005-09-02 at 11:53 +0300, Arif YILMAZ wrote:
> Hi Stefan, 
> I couldn't have a look at the chips at atmel (atmel pdfs just don't
> show up on my browser)  but as far as I know  they are not 8 pin
> devices, but they are cool as well I will consider thank you.

  Probably not your browser that is at fault.  You might want to look
into obtaining a different PDF viewer plug-in.

  As regards AVRs, yes, Atmel makes several lines of 8 pin AVR
processors,, all in the ATTINY dsignation (ATTINY11, ATTTINY12,
ATTINY15, specifically, of which I am aware, and there may well be
others).  These little processors can be amazingly useful, for akl that
they offer no more than 6 I/Os per package.  To spin off topic a tad,
and mention "THE OTHER GUYS," MicroChip actually has a line of 6 pin (!!
yes, *6*) PICs.  Very limited scope, but within that scope, extremely
useful.

Tom

--- In AVR-Chat@yahoogroups.com, "Arif YILMAZ" <arif.yilmaz@b...> wrote:
> Hi Stefan, 
> I couldn't have a look at the chips at atmel (atmel pdfs just don't 
show
> up on my browser)  but as far as I know  they are not 8 pin devices, 
but
> they are cool as well I will consider thank you.

I guess the chips are too big for a 8-pin housing.

And yes, as you mentioned the high level of the 3V3 dataflashs is 
sufficient for the AVRs to be recognized as such even for 5V powered 
uCs. Since the dataflashs are 5V tolerant as per the datasheet, there 
is no need for serial resistors as current limiters (but they won't 
hurt if not overdone - when they slow down transitions too much...).

HTH,
Stefan