Saturday, December 9, 2023

Bluetooth Serial Communications with connectBlue / u-blox OLS425

IoT – Internet of Things Forums Raspberry Pi Bluetooth Serial Communications with connectBlue / u-blox OLS425

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    Cristian Sturek

    Has anyone had any success reading on a Raspberry Pi packets sent over a SPP (Serial Port Protocol) link from an u-blox (connectBlue) OLS425 module? We’ve been trying for about a week now, with no success.

    We’ve tried this NodeJS module for serial over bluetooth, it didn’t work:

    We also tried Wireshark -> we pair -> turn on the Bluetooth listener -> it sees no packets.

    Not giving up yet. Trying this next: to see what – if anything – we can collect.


    As the forum is not monitored by u-blox, we thank you for also posting the same question on the u-blox forum ( where questions related to u-blox products are posted and consequently addressed by a competent growing community of product experts. You will get a reply there shortly.

    Cristian Sturek

    Thanks for getting back to me. The SPP on top of the GATT is what is being implemented, and that is how the temperature is being sent. Works fine, we can debug in the Android app.

    However, how do we get the same code running on Android to work on the Raspberry Pi 3? Has anyone been able to read the SPP packet (like you said, on top of GATT) via NodeJS?

    The OLS425 module is a Bluetooth Low Energy device and as such does not support the Bluetooth Classic SPP profile (the SPP profile is for Bluetooth Classic only).

    To communicate with the OLS425 module using Raspberry Pi you must use Bluetooth low energy. The u-blox Serial Port Service, which is implemented on top of the Generic Attribute Profile (GATT), can be used if you want to send serial data. Please, see the following document for protocol specification:

    u-blox Low Energy Serial Port Service – Protocol Specification

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