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CC2652P: questions related to porting TI-15.4/Sub-GHz application to ZStack/2.4GHz

Zhiyong Li (FT)
Expert 2530 points
Part Number: CC2652P

Hi,

We are planning to port our TI-15.4/900MHz based application to Zigbee/2.4GHz due to lack of mesh network implementation in that stack, have a few general questions:

1) Maximum allowed transmission power allowed to pass FCC certification

CFR Title 47 15.247 states that the transmission power can go up to 1watt if frequency hopping or digital modulation is utilized. Apparently TI zstack doesn't implement frequency hopping for 2.4GHz radios. So my questions here are:

1a): does ZStack implement some sort of digital modulation? I assume DSSS in the Phy Type means some sort of digital modulation.

1b) does 1watt translate to 20dBm in CC2652P launchpad based application? Any other factor to consider except reducing TX power for higher frequency channels as stated in user guild?

2) Power consumption of end device

We have very good power consumption numbers with CC13-90 radios when they are properly configured. My question here is: are power consumption of sleepy zed similar to sensor nodes in TI-15.4/Sub GHz? I tried to find some test results of example zed projects but I may have missed them.

3) Dynamically switch between sleepy end device and router

According to this post and other literature I have read so far, the role of a radio is determined at the time of firmware compilation, and TI doesn't provide out-of-box support for switching roles after firmware has been built and flashed into a radio.

But the linked post seems to imply it is possible to customize the firmware of a router and make role switch possible. Can someone confirm if this true? I can see this feature useful for our application, and if true, may put it on the list.

4) Maximum number of devices in a network

The default number of maximum number of device is 20, and 40 for TC link keys, with a theoretic limit at 65536. My question here is, what is the practical limit? We were advised to set maximum number of devices in a sbu-GHz network to 50. Is 50 or larger in ZStack network possible or advisable? Should we proportionally increase maximum number of TC link keys, NVS pages, and others?

Please advise,

Thanks,

ZL

  • +1
    TI__Guru**** 202776 points

    Hi Zhong,

    You can wait until the SimpleLink Zigbee Stack supports R23 at which point Sub-1 GHz (aka Suzi) mesh operation is added.  However, the date of this update is unavailable.

    1) Zigbee supports the IEEE 802.15.4 2006 PHY: 250 kbps, OWPSK, DSSS=1.8.  20 dBm is mathematically equivalent to 0.1 W, although I do not understand how this is relevant for your SimpleLink device.  The CC2652P high PA is configurable by 6 dBm up to 20 dBm, both 6-10 dBm and 14-20 dBm power tables are supported in the SDK.

    2) Zigbee sleepy end devices are equivalent to 15.4-Stack sensor nodes where power consumption is concerned.  You can review SWRA625 and the Z-Stack User's Guide.

    3) You can reference the ZNP as a multi-role example, however it does not include a ZCL application so further modifications would be required.  You would also need to reset the device to factory new (including removing prior Zigbee network information and a soft reset of the device) to switch roles before joining the network, given that other Zigbee routing devices do not expect a node to change roles entirely during runtime.

    4) Estimation: Up to 80 is possible with the default NV settings, but up to 200 can be achieved with significant modifications.  See SWRA650 and the Z-Stack User's Guide.

    Regards,
    Ryan 

  • 0 in reply to Ryan Brown1
    Expert 2530 points

    Hi Ryan,

    I remember that you answered quite a few of my questions related to sub-GHz radio, so thanks again.

    Do you have any rough estimation on release date of Zigbee support of R23? Sometime in 2024? It will be really nice to have Zigbee on Suzi. Will it support 50kbps? we don't need much bandwidth but will appreciate the increased range or reduced power consumption for the same range.

    Ryan Brown1 said:
    20 dBm is mathematically equivalent to 0.1 W, although I do not understand how this is relevant for your SimpleLink device. 

    I was just trying to confirm that if we set transmission power at 20dBm and we can still pass FCC certification test. I would assume so, because 20dBm is an available option. But we cannot set tx power at 14dBm without frequency hopping. Hence the question.

  • +1 in reply to Zhiyong Li (FT)
    TI__Guru**** 202776 points

    I highly recommend that you consider the DSR zboss solution, which includes Zigbee R23 support and Sub-1 GHz operation for SimpleLink CC13X2 devices.  Suzi operation supports 100 and 500 kbps 2-GFSK PHYs as I recall from the Zigbee Specification.  You can contact the CSA for the Zigbee PRO R23 Specification and compare that against the FCC requirements.  Here are descriptions for both DSSS and GFSK.

    Regards,
    Ryan