TWR with more than 10 anchors

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cgentner
Beginner
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Joined: Tue Jan 09, 2018 2:52 pm

TWR with more than 10 anchors

Post by cgentner » Tue Jan 09, 2018 3:05 pm

Hi all,
I want to use more than 10 anchors for positioning, placing them in different rooms.
If I set the anchor number to e.g. 12 everything works fine until I disconnect and reconnect the power source. After reconnecting the power source the anchor address is always set to 10 (0xA).
Is it possible to use more than 10 anchors (or more than 6 as it is implemented)?
Thanks.

arnaud
Bitcraze
Posts: 1664
Joined: Tue Feb 06, 2007 12:36 pm

Re: TWR with more than 10 anchors

Post by arnaud » Wed Jan 10, 2018 9:11 am

Hi,
What you are trying to do is possible in theory, but the way we implemented setting the anchor address does not allow you to set an address above 9 since we are using single key press for setting the address (an oversight on our part ....).

I am creating a ticket and will start to look at implementing setting higher addresses: https://github.com/bitcraze/lps-node-firmware/issues/23. In the current system it should be possible to use up to 256 anchors. More is possible with a bit more changes (in some part of the code there is an assumption that an anchor ID is one byte, it would not be so hard to increase but 256 anchors should be enough for now, if not, lets fix it :-).

On a side note, this is a nice project, setting-up a multi-room system is something I wanted to do but never had time. I am interested if you can share updates later in the project. Are you planning to interrogate only anchors that are in the same room as the CF?

cgentner
Beginner
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Joined: Tue Jan 09, 2018 2:52 pm

Re: TWR with more than 10 anchors

Post by cgentner » Thu Jan 11, 2018 10:59 am

Thank you very much for your reply. We are currently using 12 anchors and one node. We fixed it with a workaround and we are now able to use all of them. At the moment we are planning to use all of the anchors which are reachable. Hence, some of them could be located in a different room and the direct path between the anchor and the node could be blocked, so we would get biased measurements. Hopefully our algorithm is able to deal with the biased measurements. I'll keep you updated.

sypark921
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Joined: Mon Oct 16, 2017 5:26 am

Re: TWR with more than 10 anchors

Post by sypark921 » Fri Jan 12, 2018 6:46 am

hi, i have a question.

refer to :

https://github.com/bitcraze/crazyflie-f ... deck.c#L92

if i add the ninth Anchor, The anchor address can be predicted to be 0xbccf000000000008. But. 0xbccf000000000008 is the tag address.

How can i solve this problem?

arnaud
Bitcraze
Posts: 1664
Joined: Tue Feb 06, 2007 12:36 pm

Re: TWR with more than 10 anchors

Post by arnaud » Tue Jan 16, 2018 9:28 am

@sypark921 Currently the only way to change the tag address is to modify it in the source code and recompile the firmware. It is not so much of a problem when in TWR though since the anchors are going to ignore TWR messages that are for the tag.

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