802.15.4 blind broadcast loop

RE: 802.15.4 blind broadcast loop

Edvin — Thu, 04 Oct 2018 08:17:23 GMT

I see. Yes. It makes sense. Just be sure that when they wake up, they listen to the FFFF channel long enough to pick up at least one of the messages before going back to sleep. Maybe even a couple of messages, in case the first message is not picked up properly.

Best regards,

Edvin

RE: 802.15.4 blind broadcast loop

TahuIndy — Wed, 03 Oct 2018 17:22:08 GMT

Good to know. For our design we are planning on having up to 64 battery operated child nodes. They will power up un-assigned, then negotiate to be added to the PAN controller node. They will then sleep for 99% of their lifetimes. Only waking up for a small time and picking up a 0xFFFF broadcast message with a bitmask payload. They will check this bitmask to see if they are required to take action. If they need to wake, they will then start several message communication with the PAN controller.

Does that design make sense? I don't think we will ever want 2 locks nodes to be duplicated. In fact, that would be very bad :P.

RE: 802.15.4 blind broadcast loop

Edvin — Wed, 03 Oct 2018 12:16:07 GMT

Hello,

Glad to hear that you found the solution.

As you say, this channel is typically used for formation of networks, since it is an open channel. Other than this being a typical broadcast / subscription channel, which means that others may hear your data, and there may be some noise on this channel.

FYI:

It is possible to have several devices listening on the same channel. E.g. if you flash two devices with the wireless_uart\raw\second, and one device with wireless_uart\raw\first, then messages sent from "first" will be received on both "second"s, and a message sent from any "second"s will be received on "first".

Best regards,

Edvin

RE: 802.15.4 blind broadcast loop

TahuIndy — Tue, 02 Oct 2018 17:10:07 GMT

Found my answer through some more digging into the 802.15.4 specification. Looks (and verified) that setting the dst_addr.short_address to 0xFFFF is the key to open/blind broadcast and reception. So, the key then becomes creating/provisioning a PAN_ID and using the MAC addresses of each device to "white list" each other as the network is formed.

Anyone know if using 0xFFFF has other downsides or reasons that it's a bad idea in a commercial environment?