BLE advertising : Minimum packet length ?

[Altron]

Hello,

I'm a beginner on BLE protocol and i would like to send data during approximately 4us,stop it during the same time and transmit signal again during 4us and so on.

This mean that advertising packet will be less than 1byte (8us). Is it possible to do make fragmentation ?

Help me please, i need to this on smartphone application.

[AmbystomaLabs]

BLE broadcasts a preamble and sync word prior to the packets as do most wireless protocols.

These alone are longer than 8usec.

[Altron]

Thanks :)

As i said i don't want to establish connection between 2 devices. Do you have a idea of how can i turn on a sensor with a perdiodical signal at 120KHz through the smartphone, no matter the communication protocol (WIFI or BLE) and the transmitted data frame ?

The receiver (sensor) can only detect this signal.

[AmbystomaLabs]

There is nothing on a smartphone that operates at that rate. Modern smartphones have BLE v4, maybe BLEv5, traditional bluetooth BR/EDR, some phones have ANT, most have NFC, 802.11b,g,a,an, ac (ie, WiFi). They also have 2G/3G/4G/LTE modems but you won't be able to access them.  They just serve to provide a data path that you don't really control.

Anyway, nothing on a smartphone operates at 120kHz for the minimum basic time slot or packet length (as the case may be since these are a mix of random access and time division protocols).

If you really have to have 8usec bursts of data you will have to do some custom device that you hang off of the USB port on the smartphone. You will likely have to come up with your own protocol for the transmission or repurpose an existing one. Since it is custom you can probably do a wideband solution then you can send well formatted data in that 8usec burst with synchronization, channel equalization and FEC data.

But again this well be custom hardware at both ends.  You can't get a stock SoC like nRF to do this.

I think if we had a better idea of your application we could assist. But your requirements are a little vague. Normally if you are sampling data at 120kHz you would just buffer and periodically broadcast en masse the accumulated data. That you actually can do with BLE.