Transmitting using 802.15.14 GTS

[nabil]

Hi,

I'm having trouble transmitting packets with GTS enabled using Nordic's IEEE 802.15.4 MAC library. I don't have an isolated sample app I can post yet so I'll just describe the call flow for now.

I'm setting the follow PIBs:

PHY_CURRENT_CHANNEL_ID
MAC_SHORT_ADDRESS
MAC_EXTENDED_ADDRESS
MAC_PAN_ID
MAC_RX_ON_WHEN_IDLE - enabled
MAC_ASSOCIATION_PERMIT - enabled
MAC_GTS_PERMIT - enabled

The PAN coordinator starts broadcasting beacons:

    static mlme_start_req_t start_req =
    {
        .pan_id  = CONFIG_PAN_ID,
        .logical_channel = CONFIG_TEST_CHANNEL,
        .start_time = 0,
        .beacon_order = 2,
        .superframe_order = 1,
        .pan_coordinator = true,
        .battery_life_extension = false,
        .coord_realignment = false,
#if (CONFIG_SECURE == 1)
        .coord_realign_security_level = false,
        .beacon_security_level = false,
#endif
    };
    mlme_start_req(&start_req, mlme_start_conf);

Device 2 performs a beacon scan and successfully associates with the PAN. The same device then requests a Tx only GTS successfully. At this point attempting to transmit with GTS enabled returns MAC_INVALID_GTS. I also tried polling the coordinator for data using mlme_poll_req(). The coordinator receives the request and I transmit a packet back, but device 2 doesn't received the data.

Is there anything wrong with this sequence of events?
Can Nordic provide any sample code using beacons and GTS?

Nordic SDK version: 15.2.0
Sample code based off 802.15.4 Uart example

Thanks

[nabil]

Quick update: I'm now able to request a RX only GTS from the end device and send data from the PAN coordinator. The PAN coordinator stops transmitting after about 160 seconds.

I was not able to request a TX only slot and transmit from the end device yet. I hit an assert in source that is not visible to me. I've tried broadcast and sending data to the coordinator.

[nabil]

Hi Nordic,

Can you confirm if it is possible to send broadcast packets from an end device in a GTS?

[AndreasF]

Hi.

If you look in IEEE 802.15.4-2006: 7.5.7 GTS Allocation and Management:

IEEE 802.15.4-2006: 7.5.7 GTS Allocation and Management said:

A GTS shall be allocated only by the PAN coordinator, and it shall be used only for communications between the PAN coordinator and a device associated with the PAN through the PAN coordinator.

It means that broadcast packets cannot be sent using GTS - GTS should be used only for unicast packets to or from PAN coordinator.

Best regards,

 Andreas