[U-Boot-Users] why eeprom vs flash

[Wolfgang Denk]

In message <9e4733910802141038h16afb653l8b6c8a0181ea109f at mail.gmail.com> you wrote:
> I'm new to working on low level code like u-boot. Something I don't
> understand is why things like the Ethernet address are stored in
> eeprom instead of flash. Is this something to do with how boards are

This may have h/w design reasons. For example, you may want  to  have
things  like  serial  number,  MAC address and other similar settings
stick with a device even when you change  the  CPU  module;  in  such
situations it's much easier to place a EEPROM somewhere in the device
itself;  with  a I2C bus you need only 3 wires. If you try to use NOR
flash in a similar configuration, you have to route the full data and
address bus and some other signals, which is much more expensive.

> manufactured? From a high level perspective it doesn't seem to matter
> if eeprom or flash is used.

Well, it does matter. Flash is much more reliable. Read  for  example
doc/I2C_Edge_Conditions  what  can (and does!) happen to I2C attached
EEPROM devices. And with flash, we can even  store  the  data  redun-
dantly, so you have really good reliability.

Best regards,

Wolfgang Denk

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