Re: [lwip-devel] 6lowpan support in lwip

[Sergio R. Caprile]

Hi,

> We couldn't understand your following statement:
> "The 6LowPAN code is implemented like a netif, but you'll have to implement 
> your own driver for your PHY/MAC. I used an AT86RF231, so you need to write 
> the driver to write the packets via SPI. That depends on your CPU and your 
> external PHY."

The netif is the layer-2-like part of lwIP. The driver for an Ethernet
chip, for example is a netif.
The 6LoWPAN code itself is written as a netif, lwIP sees it as an
interface carrying IP datagrams.
You have to write the code to interface to whatever you physically use
to carry the data, be it SPI or parallel or on-chip (also parallel...)
or ...

> ->We understand we will have to write driver for our 802.15.4 device which 
> will speak with 6LowPAN driver. Is this correct?

Exactly. I can't tell you more because I don't know. Let's wait for Ivan.
I still don't have my hardware ready, but I'm willing to help with this.

> -> We are having a setup running in which our application payload gets 
> transferred from one device to another over ZigBee and Bluetooth.
>       We now want to create an IP packet on the device itself and use ZigBee 
> / Bluetooth to just transfer the data from one device to another using LWIP + 
> 6LowPAN.

AFAIK, 6LoWPAN is IPv6 over 802.15.4. If you want to carry it over
ZigBee, you have to implement ZigBee IP, which is pretty much the same,
but you better check for compatibility.
As for Bluetooth, that is 6LoBT, different animal, can't tell you how
much they share. I do know 6LoWPAN makes heavy use of 802.15.4
addressing, so I don't bet changes would be trivial.

> As of now we are unable to get a clear picture of how the packet flow from 
> Application to RF device/driver goes?
> Reason: we don't have a 6lowpan integrated lwip code along with a test 
> case/app.
> It would be really helpful if you could send/share with us your basic 
> software stack in which an application level payload goes through LWIP + 
> 6LowPAN+MAC /PHY Radio layer.
> We can then migrate it to our radio device which can be a Bluetooth/ZigBee 
> device.

If you would like to open a thread on the users list (lwip-users at
nongnu.org), we can have a conversation on this very subject and the
rest of the lwIP usage guidelines there. (I would jump in tomorrow)

Regards