Limit on # of Decks?

Firmware/software/electronics/mechanics
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ryanemp
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Limit on # of Decks?

Post by ryanemp » Wed Jan 02, 2019 5:12 pm

Hello and thank you in advance for your help!

I've been flying and enjoying it and now ready to start toying around with some of the decks. The limits seem endless , but I thought it would be a fun project to have the CF do the following:

Detect walls (using the multi-ranger deck and Flow Deck) and then use that distance measurement to try and home it to a Qi Wireless station.

I've been looking for similar posts and FAQ but didn't see anything. I'm sure others have been working on something similar so wanted to see if it's possible to add multiple decks in that configuration? Is there any limitation to the decks I'm not thinking of? (Of course, weight would at some point be the issue)

Thanks for reading and any help you can provide.



jgsuw
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Re: Limit on # of Decks?

Post by jgsuw » Wed Jan 02, 2019 7:12 pm

Hello there!

Stacking multiranger, flow, and QI charging decks should be fine, provided that you have headers which are long enough. The trick with adding decks is that the Crazyflie has limited input-output capability. Each new deck will require some of that capability, and not all of the IO capabilities can be shared by multiple decks.

I have been building custom decks for my crazyflies for the last two years. When I need to add a new deck, the first thing that I do is look at the expansion header on the schematic for crazyflie 2.0 (first page, bottom right corner), as well as the schematics for any decks that I am using (usually this is just the flow deck). That gives me a quick reference for what IO pins are being used by the decks I am using, as well which IO are still available for future decks.

Some of the IO capability of the crazyflie can be shared across decks. Specifically, the I2C and SPI communication busses can communicate with multiple decks, with some limitations. If you aren't familiar with how these busses work, I highly recommend you read up on the basics of I2C and SPI. Other capability can not be easily shared by multiple decks, such as the analog inputs, or the UART busses. Hence, if you want to design a system which uses these pins then you must think carefully about how they are allocated to decks.

I hope you find this response helpful!

ryanemp
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Re: Limit on # of Decks?

Post by ryanemp » Wed Jan 02, 2019 9:10 pm

That's great info, yes very helpful! Thank you very much for taking the time to lay that out , that all makes sense.

tobias
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Re: Limit on # of Decks?

Post by tobias » Fri Jan 04, 2019 1:51 pm

Just a correction on the great explanation. Even though the Qi and the Flow works together electrically they don't work together mechanically as the Qi will block the camera and distance sensor.

droneguy
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Re: Limit on # of Decks?

Post by droneguy » Fri Jan 04, 2019 3:35 pm

We've been working on a custom solution for this for the past few months and its being tested for right now - if there is sufficient interest, we would consider open sourcing the design.

Stay tuned...

jgsuw
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Re: Limit on # of Decks?

Post by jgsuw » Fri Jan 04, 2019 11:43 pm

Just a correction on the great explanation. Even though the Qi and the Flow works together electrically they don't work together mechanically as the Qi will block the camera and distance sensor.
Thank you for the correction! I suppose the Qi deck needs line-of-sight to the charging pad, is that correct?

arnaud
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Re: Limit on # of Decks?

Post by arnaud » Mon Jan 07, 2019 10:31 am

The Qi deck needs to be very close to the charger in order to work and it does not have through-holes to mount a deck bellow it so it needs to be the deck at the bottom.

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