nRF52840 many to one streaming data and time synchronization

RE: nRF52840 many to one streaming data and time synchronization

ovrebekk — Wed, 26 Apr 2023 12:10:04 GMT

Hi Frank

Sounds good. If you have more questions or comments just let me know 🙂

Best regards
Torbjørn

RE: nRF52840 many to one streaming data and time synchronization

meyiao — Wed, 26 Apr 2023 01:54:52 GMT

Hi Torbjørn

Thanks a lot, I'll test this code as soon as possible.

Best regards

Frank

RE: nRF52840 many to one streaming data and time synchronization

ovrebekk — Tue, 25 Apr 2023 07:47:40 GMT

Hi Frank

Please find the modified version of the library here:

devzone.nordicsemi.com/.../6471.nrf_5F00_esb_5F00_mod.c

Please be aware that I haven't done extensive testing of this library, so it is important that you test it well on your side. The library is provided "as is", with no guarantee of correct functionality or support.

Going forward all of the ESB developments will target the nRF Connect SDK, and you might want to migrate to this SDK at some point.

Best regards
Torbjørn

RE: nRF52840 many to one streaming data and time synchronization

meyiao — Mon, 24 Apr 2023 11:08:57 GMT

Hi Torbjørn

I'm using nrf52 SDK 17.0.2

Have a nice day.

Frank

RE: nRF52840 many to one streaming data and time synchronization

ovrebekk — Mon, 24 Apr 2023 10:22:28 GMT

Hi Frank

Which SDK version are you using?

Best regards
Torbjørn

RE: nRF52840 many to one streaming data and time synchronization

meyiao — Fri, 21 Apr 2023 16:29:12 GMT

Hi Torbjørn,

You are so kind. I'd love to test your new code. How can I receive your code?

Best ragards

Frank

RE: nRF52840 many to one streaming data and time synchronization

ovrebekk — Wed, 08 Feb 2023 06:08:58 GMT

You welcome Frank 🙂

If timing gets tight with the ESB library I recently made a small change to the library in order to enable the fast rampup mode in the radio peripheral. This reduces the radio startup time from 130us to 40us, and will reduce the total time of sending a packet and receiving an ACK by about 180us.

At some point I hope to get this change into the official libraries, but until then I can share the code with you if you need it.

Best regards
Torbjørn

RE: nRF52840 many to one streaming data and time synchronization

meyiao — Wed, 08 Feb 2023 02:18:29 GMT

Very very helpful, thank you so much! I'll try to do some experiment following your instructions!

Have a nice day!

RE: nRF52840 many to one streaming data and time synchronization

ovrebekk — Tue, 07 Feb 2023 13:54:32 GMT

Hi Frank

[quote user=""]Which protocol shall I use, ble or esb? each tracker shall send at least 50 packets per second, and it's even better if we can achieve 100 packets per second.[/quote]

100 packets pr second from 8 devices is beyond what you can do with BLE, but with ESB it should be possible.

[quote user=""]In order to fuse these data to calculate human motion, the timestamp of trackers shall be synchronized! I think I can send timestamp from the master to the trackers in a lower rate. Can I achieve that using ESB? How can I send data from receiver to transmitters simultaneously?[/quote]

ESB uses a feature called ACK payload to allow you to embed data in the acknowledgement packet, which is sent as a response to the packet from the PTX. This allows the PTX and PRX to exchange data bidirectionally.

I think the easiest way to synchronize the 8 devices is to have the receiver be the PTX, and the trackers be the PRX's. Then the receiver can simply poll each of the 8 trackers in turn. You can then also include a timestamp in the packet from the PTX, which the trackers can use to update their local timers.

There should be enough time to send a small packet from the PTX to each of the trackers, and receive a 23 byte response, in 10ms, as long as you set the automatic retransmit counter to 0.

Another advantage of ESB over BLE is that you have more precise control over when the RF packets are sent, which makes it easier to achieve accurate synchronization between the PTX and the PRX's.

Best regards
Torbjørn