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Reference starting point for Sub-GHz mesh? Preferably 6LoWPAN

Anup Rajput
Expert 1920 points
Other Parts Discussed in Thread: CC1200, CC1120, CC1101, CC2538, CC1310

Hi,

Our products right now communicate either over RS-485 or GSM (both built on MSP430s). Our recent customers have required wider coverage (in terms of distance between nodes) as well as much larger number of nodes, because of which a GSM gateway for every node is prohibitively costly and RS-485 too messy (in terms of installation and maintenance).

Hence, we decided to build our own mesh of general purpose nodes while using a Sitara AM335x based edge router. I'm sure this is pretty much what everybody is doing these days, and so are we!

We have chosen CC1200 as the radio for our first version of the device, and are pairing it with an FRAM MSP430.

We have seen way too many implementations for 2.4GHz for mesh (over Zigbee or otherwise), but haven't seen anything substantial on ti.com for Sub-GHz. Do you have a suggested example solution that we could use as a starting point?

I know that I've probably asked a very open ended question here but since re-spinning a PCB is less costly than spending time on a non-ideal solution, we would be glad to start/re-start on the right footing.

Also, how does one choose between a CC1200/CC1120?

  • 0
    TI__Genius 12480 points
    Hello Anup,

    You talk about Edge Router, so I guess you are interested in a IPv6/6LoWPAN based solution ;)

    Open Source Contiki OS (www.contiki-os.org) are about to get official support for both CC1101, CC1120 and CC1200. Please see this pull request for cc1101 and cc1120 support: github.com/.../1002

    CC1200 driver support is about to come on a new platform using cc2538 as host MCU (and RF if using 2.4GHz) and cc1200 for sub-1GHz support. Internet/backbone connection will be via the ENC28J60 Ethernet trx. I expect this to be included in Contiki in the coming month.

    When it comes to cc1120 vs. cc1200 I would recommend cc1200 for full IEEE802.15.4g support, new PHY settings and MAC frames.

    /Jonas
  • 0 in reply to Firefighter
    Expert 1920 points
    Hi Jonas,

    Thanks for the response.

    Yes, we are indeed looking at 6LoWPAN. And, from your response and our own research (read: Google-ing), it seems Contiki is the way to go. Their license terms also seem appropriate for commercial (but free) usage.

    So, CC1200 it is.

    Regarding the CC2538 as a platform, wouldn't we be paying for the in-built 2.4GHz and Zigbee support compared to an MSP430/Tiva based platform where we get a general purpose MCU with many more features? Is the CC1200 driver available in any form right now, so that we can start porting it to an MSP430? I'm sure porting it to a Tiva would be trivial, since it is also a Cortex M processor? Or is there more to it in terms of hardware support built on the CC2538, that the CC1200 wouldn't provide by itself?

    Also, since you mention the ENC28J60 Ethernet IC, and I see something similar on the github commit thread you have linked to, would this mean that we wouldn't even need a TI Sitara?

    PS: Not marking as Verified Answer yet so that the thread doesn't become stale.
  • 0 in reply to Anup Rajput
    TI__Genius 12480 points
    Hi,

    You can for sure get the same or more functionality with e.g. a TIVA or MSP43x, porting the drivers should be straightforward as you say.

    I expect the CC1200 driver to be pushed to Contiki any day now...

    You can build a 6LoWPAN Edge Router without a Linux machine, the main issue is the RAM - each route/routing entry requires RAM (about 80 bytes). For example the 6lbr solution is supporting cc2538 as Edge Router: github.com/.../CC2538DK-Software-Configuration

    Cheers!
  • 0 in reply to Firefighter
    Intellectual 660 points

    Hi Anup,

    have you considered the CC1310 which combines the MCU and sub GHz radio as an SOC?

    @Jonas, do you have any idea whether the pending Contiki driver support would extend to this device (presumably based on the CC1200)

  • 0 in reply to Firefighter
    Expert 1920 points

    Hi Jonas,

    Thanks for the details. I think we could rely upon something like a TIVA easily then, and have a more "embedded" edge router that way. We will give it a shot.

    Hi Phil,

    The device is still in preview, so we haven't tried it yet. But we have it in mind for the future. Would be glad to follow your experience on this device.

  • 0 in reply to Phil Vergers
    TI__Genius 12480 points
    Yes, we do plan to add cc13xx to Contiki (hopefully it will be embraced by the Contiki community :))