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Evaluate the maximum working connection to a BLE central (Dongle or cellphone)

TTN

Hi,

Currently, we have a device that uses the nrf52832 custom board as a Peripheral notify to send the data collected to Pixal 5 (central),

We have a cellphone app to call the data received by the mobile phone to show that at present,

we need to evaluate how many peripherals can be connected to a central and can also operate normally.

I would like to ask how to evaluate and compare Pixal 5 and nrf 52840 dongle as BLE central.

What about the maximum number of connections in operation?

At present, a peripheral will transmit(MTU) 200 bytes of data 10 times per second, 10 sets (2000 bytes) of data will be 2 Kbytes,

  • 0

    There is no definitive answer to this question. If you use data length extension (DLE) so that you can send the 200 bytes in a single packet, that will take about 4 ms including everything on the nRF (including everything form pre-processing to post-processing). The actual time on air will be a bit more than 2 ms, and as the smart phone is the central this may be closer to the relevant number. If everything works out and each peripheral transmits data 10 times a second that means that in theory you could fit close to 50 peripheral connections on the central. The real number will likely be much lower, though, and differ from different smart phones, and depending on other tasks being currently done (particularly BT or WiFi activity).

  • 0 in reply to Einar Thorsrud

    Hi,

    Thanks for your reply.

    If we use nrf52840 Dongle as central and connect to a device to replace the device's bluetooth module.

    Or we can write an application in the dongle, the dongle use uart as protocol to device ,

    are these two applications workable? 

    Any solutions which we can test?

  • 0 in reply to TTN

    I did not fully understand this. Can you rephrase/elaborate?

  • 0 in reply to Einar Thorsrud

    Hi,

    I have a android device(bluetooth module version is 4.0)

    I want to change the device's device module by use nrf52840 dongle.

    If i use the android app nrf connect can the app use nrf52840 dongle as the device's bluetooth module?



  • 0 in reply to TTN

    Hi,

    TTN said:
    I want to change the device's device module by use nrf52840 dongle.

    Do you want to replace the Pixel 5 and use the nRF52840 dongle as central instead?

    TTN said:
    If i use the android app nrf connect can the app use nrf52840 dongle as the device's bluetooth module?

    If the above is the case, and you want to replace the Pixel 5 with a nRF52840 dongle, then you cannot use the nRF Connect app anymore. You would have to write your custom firmware for the nRF52840 dongle, or alternatively use the pc-ble-driver to write a PC side application (or if you use Linux, use BlueZ and program a host on the nRF52840 dongle).

    I am still not sure if this is what you want though, so if this does not answer the question then please explain more what you want to do.

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