Newbie questions: how does UEXT work?

Started by OpenMind, January 01, 2014, 12:06:22 pm

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OpenMind

Hello there!

I am completely new to single board computers, and would like to buy and set up a simple system with Debian Linux on an OlinuXino, just to toy around a bit.

One thing I could not quite grasp so far is how exactly the UEXT modules will work.

Basically, I would like to know: if I connect a module like the Ethernet Module to an OlinuXino, are there any additional steps required to address it directly as an ethernet device under Linux? Or will the kernel directly recognize it? I did not understand if it is "plug & play" or not.  ;)

And my second question: there is the UEXTx5 port splitter. Can I use this to connect any five modules to an OlinuXino that has only one UEXT port?

I hope you can help me out with these newbie questions! That would make it far easier for me to decide which parts to buy!  :)

Best regards!

Fadil Berisha

Quote from: OpenMind on January 01, 2014, 12:06:22 pm
Or will the kernel directly recognize it?

No. Kernel will recognize only devices installed on board and UART (if any is connected on UEXT).
If you attach any i2c or SPI device on UEXT, you need to modify kernel accordingly.

Quote
Can I use this to connect any five modules to an OlinuXino that has only one UEXT port?


You can connect one SPI device, one UART device plus three i2C devices

OpenMind

Thanks for the quick reply! :-)

Quote from: Fadil Berisha on January 02, 2014, 01:29:26 amIf you attach any i2c or SPI device on UEXT, you need to modify kernel accordingly.


Is there a brief overview somewhere on how this is kernel modification done? Even though I am a Linux user, I never modified the kernel myself.

I'd like to find out if this is achievable for me, or if I should find a different solution (like, e.g., enhancing the OlinuXino's capabilities via USB).

Fadil Berisha

Quote from: OpenMind on January 02, 2014, 02:18:12 pm
Is there a brief overview somewhere on how this is kernel modification done? Even though I am a Linux user, I never modified the kernel myself.


There are two possibilities, to use old kernel based on version 2.6 or modern version 3.x based on Device Tree. New kernel missing audio, TV and power management driver. Old one support everything.

You can build kernel to boot board with/without bootloaders.
Here are some links for 3.x kernel:

https://github.com/koliqi/imx23-olinuxino
g-lab.ca
jann.cc

Search this forum for examples how to add SPI and i2c.