large data transmission through multiple characteristics

[balaji]

Hi,

How to send large amount of data, using multiple characteristics? Assume that my data size 800 bytes and characteristics with notify property. I did splitting the data as 20 byte of packets and transmit each packet using the 4 characteristics continuously until all the data's are transmitted. Here the problem i am facing is i can send hole data without any lose but i couldn't achieve the data rates as 4 packets per connection interval. Please give me your valuable suggestion.

Regards, Balaji

[KPE]

I don't think you can send more data just by using more characteristics. Each package has a payload of 20 bytes, and as far as I understand a characteristic is just a handle value sent as a part of the package, and along with, but not part of, the payload. So characteristics are just a way to indicate where the package belong, and it doesn't actually start a set of new channels operating on other frequencies or something along those lines.

At any time you can only have 6 outstanding packets going from the device to the client, which is determined by the package buffer. I don't know if you can change the package buffer, and whether if will introduce trouble doing so. Also - you might need both sides to agree on a larger number of outstanding packets before such a scenario would work.

The Gazelle protocol would be a better option (3-4 times faster), but if you really need to send a lot of data you might want to use another technology like WiFI which requires more power (though it can be turned down). But as you send data faster you are also saving power this way.

[Ole Morten]

This is quite correct, you will not get any higher throughput by having more characteristics. The quickest way to send data is to do something similar to what is outlined here: https://devzone.nordicsemi.com/index.php/dealing-large-data-packet-s-through-ble#reply-1755

Gazell is indeed faster, so if you control both ends of your link that could very well be a good option.

[Bastiaan]

Hello have you any luck with this

[Guest]

Hello have you any luck with this

[valdev]

The link ": devzone.nordicsemi.com/.../dealing-large-data-packet-s-through-ble is not available, is there any other one ?