Crazyradio PA bandwidth limits

Discussions and questions about the Crazyradio
bracco23
Beginner
Posts: 5
Joined: Tue Nov 08, 2016 9:35 am

Crazyradio PA bandwidth limits

Postby bracco23 » Tue Nov 08, 2016 9:48 am

Hello,

i'm planning to use a swarm of crazyflie 2.0 for my thesis.

Since then will be a lot i was looking on how to get more than one to communicate with a single Crazyradio PA. All the other posts are pretty old and since them support for this functionality has been added to the library and the client.

I already tried changing one of the address and using the same Crazyradio PA to communicate with more than one Crazyflie, and i was successful.

How many Crazyflie can I use on one single crazyradio? Does the radio bandwitdth (250k, 1M, 2M) has anything to do with it? Any experiment already done out there?

Thank you very much :)



arnaud
Bitcraze
Posts: 974
Joined: Tue Feb 06, 2007 12:36 pm

Re: Crazyradio PA bandwidth limits

Postby arnaud » Wed Nov 09, 2016 9:10 am

Hi,

Yes the datarate will help, you want 1M or 2M to get as much bandwidth as possible. We currently have a firmware limit at 1000 packets per second, but if you run 250K, sending the maximum sized packet will take more than 1ms.

The amount of Crazylie you can control per Crazyradio depends of what you are communicating. You can count on 1 packet per millisecond max (2 broadcast packets with a recent change to the Crazyradio), so if you need to send the position to the Crazyflies this will be the limitation (for example if you are using a mocap system).

Wolfgang from USC has the most experience there: I think he has run Crazyswarm, a swarm of 49 Crazyflie 2.0, with 3 Crazyradio (this needs to be confirmed though).

If your swarm is more autonomous (like with the LPS, where crazyflies calculate the position estimate and all we have to send is high-level setpoint), it should be possible to control more quad per Crazyradio.

Best,
/Arnaud

whoenig
Expert
Posts: 208
Joined: Mon Oct 27, 2014 2:55 am

Re: Crazyradio PA bandwidth limits

Postby whoenig » Wed Nov 09, 2016 4:39 pm

Hi,

Some raw bandwidth measurements were done for the original Crazyradio + Crazyflie 1.0: http://liu.diva-portal.org/smash/get/di ... TEXT01.pdf. This should be similar for the current version since the Crazyradio PA uses the same chip.

For the Crazyswarm, we control about 15 Crazyflies per radio. This allows us to broadcast an external position update at 100 Hz. The actual trajectory to fly is largely hard-coded though. If you need to send different data, you might need more or less radios.

Best,
Wolfgang


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