[En-Nut-Discussion] Unnecessary writing accesses to the eeprom while saving of the network config

Harald Kipp harald.kipp at egnite.de
Wed Jan 27 10:52:28 CET 2010

Hi Ulrich,

Ulrich Prinz wrote:
> The MAC 
> had become part of the system config as it is flashed at production like 
> serial-number, product number and product name. This is very practical 
> as you can do firmware-update without loosing important device specific 
> information. And you don't have to program a second memory device (i.e. 
> EEPROM) in mass production process.

I agree, specifically the MAC address should not be part of CONFNET.
Some systems use an EEPROM attached to the network controller (Charon 2,
Ethernut 5), which allows the controller to automatically set it after

> I faced a second problem in the Nutconfig, for not showing the addresses 
> where these config areas are stored. This should be fixed too.

Not sure, if I understood. There is CONFOS_EE_OFFSET and CONFNET_EE_OFFSET.

However, I admit that I usually do not change them.

> And then there was an issue with external memories that need a bus that 
> has to be initialized before. I think it was the SPI subsystem that was 
> not ready early enough to fetch the config out of a serial FLASH chip.

The EIR and Ethernut 3.1 (not 3.0) is using the DataFlash. It works here.

However, I admit that the code is anything else but clean.

> A simple example for the config mess was a subcontractor who finally 
> modified the linker script to keep the first sector free for config 
> savings and place the code at a higher address...

Pragmatic solution. ;-)


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