[En-Nut-Discussion] Memory card issues in EIR

[Harald Kipp]

Hi Antti,

Antti Olavi Ahola wrote:
> I tried to write onto sd card using the sample code on ethernut  
> webpages but execution halts at:
> if (NutRegisterDevice(&devNplMmc0, 0, 0))

NPL stands for Nut Programmable Logic and is used on boards with 
customizable CPLD/FPGA chips only, like Ethernut 3.

The situation for PHAT on the EIR is a bit weird right now. The SAM7SE 
provides one SPI only, which is used for the VS1053 codec and the 
DataFlash. In order to allow MP3/Ogg streaming from the MMC to the MP3 
decoder, this SPI has been intentionally not connected to the MMC.

The original idea was to use SPI over SSC for the card socket. However, 
this seems to be a bit tricky. It worked basically. Until all problems 
are solved on the SSC interface, bit banging is the only choice. This 
requires some settings in the Configurator. I just tested that and it 
didn't work here. I have to come back to you.


> One more thing; the eir example application have hackish initiation  
> function (see below) which I thought might be the cause but when I  
> disabled it(and basically all other unrelated code), the application  
> froze even earlier before any memory card related code.

This is for SPI initialization, used with audio decoding and DataFlash 
access. Actually the main problem is, that Nut/OS doesn't provide a 
general bus driver concept right now and hacks are often required to 
make SPI, I2C, USB etc. working.


> Ps. Stupid question but I don't want to break the house of cards that  
> is my environment: is it safe to update nut/os just by copying new  
> sources over old ones and rerunning the nutconfigure?

Not sure if I understood this correctly. It is generally save to install 
a new Nut/OS version over an existing one and use the Configurator to 
update the libraries. Though, I'd recommend to use a new folder for each 
version. So you are able to switch between them. On Windows this is 
simply c:\ethernut-4.6.3 or c:\ethernut-4.6.4. On Linux you should 
create ~/ethernut/ and unpack the archives in this directory. So you get 
~/ethernut/ethernut-4.6.3/ or ~/ethernut/ethernut-4.6.4/. Use the 
symbolic link nut to link to the current version, which will be 
accessible via ~/ethernut/nut/. Call the Configurator after changing to 
~/ethernut/. You build directory will be ~/ethernut/nutbld/ and your 
application tree ~/ethernut/nutapp/.

When changing versions, it is not only required to re-build Nut/OS, it 
is also advisable to re-create the sample directory. If you changed any 
application sample, the Configurator will not touch them.

On Windows you need to create a new sample directory and copy your 
changes from the previous version's directory.

There are other ways to deal with updates, but from our experience this 
works best. We are switching between versions quite often.

If you want to modify Nut/OS library modules, you shouldn't do this in 
the source tree. Better copy the original Nut/OS file to your 
application directory and add it to the application's Makefile. This way 
your local version will replace the Nut/OS library module.

Harald