nRF8001 What is the maximum data rate with peered device?

RE: nRF8001 What is the maximum data rate with peered device?

chibitotoro — Thu, 17 Aug 2017 13:05:33 GMT

I'm trying to use this as a solution for transmitting SteamVR positional information to a mobile device. In my 20 byte packet im packing the following:

0: Device ID
1-4: translation X float value
5-8: translation X float value
9-12: translation X float value

For a total of 13bytes out of the 20bytes allotted. My data is being fed from Serial USB and I'm transmitting this information to my mobile device as fast as I can. I've tried the follow:

Changing Serial baud rates
Setting Serial timeouts to low value
adjusting SPI clock dividers
commenting out code to buffer untransmitted data

All of which yielded roughly around 30fps of data received at the mobile device although my experience was running at 60+fps on my zenfone AR in a fairly empty VR scene.

I'm going to try to use wifi now. But it seems pretty consistent with the data provided above.

RE: nRF8001 What is the maximum data rate with peered device?

Pablo Garcia — Wed, 28 Aug 2013 06:55:07 GMT

Now that we understand the theory behind the communications using BLE and the nRF8001 stack, I would like to state clear the theoretical and experimental numbers. I think it is a really valuable information for the community of developers:

nRF8001 Max Throughput: It can send only one packet and receive two-three packets for each connection event. Each packet contains 20 bytes.

Theory:

With iOS, this becomes 0.67 kBps or 1-2 kBps (or 5-6 kbps and 10-16 kbps), given a 30 ms connection interval.

Actual/Real (measured during experiments):

Receive packets in the iPhone every 32ms. 1 packet each 32ms -> 31 packets/sec -> 620Bps -> 4960bps

Please, if anyone has a counter example, feel free to add it to these numbers. Figures for Android devices are also welcome.

RE: nRF8001 What is the maximum data rate with peered device?

Pablo Garcia — Wed, 28 Aug 2013 06:32:55 GMT

I paste a new reply from the Nordic employee who just corrected his reply:

Ole Morten44 minutes ago I just realized my calculations were wrong by a factor 8... If you read the above as kilobytes per second, not kilobits, they are correct. The throughput of nRF8001 is hence 0.67 kBps or 1-2 kBps (or 5-6 kbps and 10-16 kbps), given a 30 ms connection interval. Sorry for the confusion!

RE: nRF8001 What is the maximum data rate with peered device?

run_ar — Wed, 28 Aug 2013 05:13:31 GMT

The reason I asked about the connection interval was that I couldn’t get your numbers to add up; at 20 ms you should be able to get a data throughput of about 8*20 bits * (1000 ms / 20 ms) = 8kbit/s Notifying, and 3 – 4 times that when receiving writes from the peer.

RE: nRF8001 What is the maximum data rate with peered device?

Pablo Garcia — Tue, 27 Aug 2013 07:24:58 GMT

Around 20ms, what Apple supports (from another post):

If you're working with Apple devices, it's useful to be aware of the fact that they have their own document detailing their recommendations for connection parameters. This document can be found here: https://developer.apple.com/hardwaredrivers/BluetoothDesignGuidelines.pdf

RE: nRF8001 What is the maximum data rate with peered device?

run_ar — Tue, 27 Aug 2013 05:27:20 GMT

At what connection interval is this?

RE: nRF8001 What is the maximum data rate with peered device?

Pablo Garcia — Mon, 26 Aug 2013 12:52:19 GMT

I copy-paste from another thread. The answer may be useful here:

When talking from the nRF8001 to an iPhone:

With the nRF8001, the throughput is less, since it can send only one packet and receive two-three packets for each connection event. With iOS, this becomes 0.67 kbps notifying and 1.3-2 kbps when read.

RE: nRF8001 What is the maximum data rate with peered device?

run_ar — Mon, 12 Aug 2013 08:31:50 GMT

Hi,

The maximum data rate depends on the connection interval set by the master. With the nRF8001 you can send an average of one 20 byte data packet per connection event. With a connection interval of 7.5 ms your data rate would be about 21 kbps. If you need a higher data rate you should take a closer look at the nRF51 series. With the nRF8001 you can receive 3-4 packets per connection interval if the connection interval is 12.5 ms or slower. It is also possible to send a maximum of 2 data packets in one connection event provided no data was sent in the previous event.

Best regards, Runar

RE: nRF8001 What is the maximum data rate with peered device?

Bastiaan — Thu, 08 Aug 2013 12:35:01 GMT

I also want to know the real maximum data rate of NRF8001?If having somebody tested it, please say about.thanks!

RE: nRF8001 What is the maximum data rate with peered device?

Guest — Thu, 08 Aug 2013 12:35:01 GMT

I also want to know the real maximum data rate of NRF8001?If having somebody tested it, please say about.thanks!