[U-Boot-Users] why eeprom vs flash

[Andrew Dyer]

On Thu, Feb 14, 2008 at 1:36 PM, Edward Jubenville
<edjubenville at adelphia.net> wrote:
>  If you are designing your own board in relatively low quantities, you might
>  want to look at Maxim chip DS2502-E48.  It holds a guaranteed unique
>  Ethernet MAC address, and would save you the hassle and cost of registering
>  to get your own address block.  The chip uses the Dallas/Maxim 1-wire
>  interface which I don't think u-boot supports (at least, not at the time),
>  so I wrote a u-boot standalone bit-bang program to print the MAC address,
>  and I manually set ethaddr in the u-boot environment.

We have code in our local tree (a bit hackish) to talk to this part
and use it to grab the MAC address.  I think someone else posted
something similar to the mailing list a while back.  We have since
switched to using our own block of MAC addresses serialized into flash
during production.  If someone wants it to play with and polish up,
let me know.

As for the EEPROMs, a lot of the ugliness can be traced to the two and
three wire busses used to talk to most of them (there used to be
parallel EEPROM, dunno anymore).  I believe the EEPROM cells inside
that actually store bits are perfectly reliable.  If there was a good
way of making the write 'atomic' you could make allowances for the
system level issues.

-- 
Hardware, n.:
 The parts of a computer system that can be kicked.