BLE central support added to ArduinoBLE
This post is from Sandeep Mistry, Senior Software Engineer at Arduino.
Today, we are pleased to announce BLE (Bluetooth Low Energy) central support in v1.1.0 of the ArduinoBLE library. This major feature addition allows your Arduino board to scan for and connect to BLE peripheral devices. With one simple library, you can now use BLE to directly connect your Arduino board to:
- A smartphone, tablet, laptop or PC
- BLE peripherals (e.g. TI SensorTag) – NEW!
- Another Arduino board – NEW!
The ArduinoBLE library and new BLE central feature are supported on the following Arduino boards:
Prior to this release, Arduino only officially supported BLE peripheral functionality on these boards. A BLE peripheral is typically used to expose some sensor data or actuators to another device BLE central capable device such as a smartphone or PC. With the new BLE central functionality, you’ll be able to wirelessly connect two boards together for communication or connect to a third party BLE peripheral, such as a TI SensorTag.
We think that the ArduinoBLE library is much easier to use than anything else out there and are excited to see what you build with this new capability!
The development journey
Back in 2015, the Arduino 101 was released, based on the Curie module developed by Intel. It was the first official Arduino board with on-board BLE support. The CurieBLE library initially only supported BLE peripheral mode.
After launch, the Arduino and Intel teams worked together to design an Arduino friendly BLE API that supported both BLE Peripheral and Central functionality. This was released later in 2016 in the v2.0 of the Arduino core for Arduino 101.
The BLE features of the 101 were also incorporated into the CTC 101 kit in many classrooms around the world. Students used smartphones or tablets for exercises in the kit to interact with project based lessons running on the board. Unfortunately, Intel decided to stop producing the Curie module in 2017, bringing the Arduino 101 board to end of life.
Last year, at Maker Faire Bay Area 2018, Arduino launched two new boards: the MKR WiFi 1010 and Uno WiFi Rev.2. Both boards use the u-blox NINA-W102 as a 2.4 GHz wireless module. Initially both boards only supported WiFi using the WiFiNINA library. However, the ESP32 chip inside the u-blox NINA-W102 supports Bluetooth classic and BLE as well.
Later in 2018, the Arduino core team was tasked with adding BLE support to the MKR WiFi 1010 board so that it could be used with the upcoming Arduino Science Kit Physics Lab product. The Science Kit Physics Lab product is another educational kit, targeted for students in the classroom. We had several choices to move forward, including:
- Bridging the ESP-IDF’s BLE API’s via RPC to the main MCU that sketches run on
- Basing things on the industry standard Bluetooth HCI protocol and investing in a Bluetooth HCI host stack as an Arduino library
The first option above was expected to take an equal amount of time to the second, but also would make the BLE library exposed to users highly dependent on the underlying firmware running on the ESP32. It was also not as portable to other chip sets in the future. Thus, ArduinoBLE was created. The NINA firmware only needed small change to bridge its virtual Bluetooth HCI controller to the UART pins of the module.
Earlier this year, we released the Arduino Nano 33 IoT and Arduino Nano 33 BLE boards. Since the Arduino Nano 33 IoT uses the same chipset as the MKR WiFi 1010, things worked out of the box. For the Nano 33 BLE, which is based on the Nordic nRF52840 chip, a new Arduino core was developed for this board based on mbed OS (see this blog post for more info). mbed OS includes a radio stack called Cordio, which provides both a Bluetooth HCI link controller and HCI host. Creating a single C++ class that interfaced with Cordio’s Bluetooth HCI link layer allowed us to re-use 95%+ of ArduinoBLE on this board. 🙂
After the Nano 33 BLE started shipping, there was even more demand for BLE central support. So, development for feature was scheduled and is now available. It combines the API designed for the Arduino 101 in CurieBLE ported on top of ArduinoBLE’s Bluetooth HCI host stack.
Many thanks to Tom Igoe, one of the co-founders of Arduino, for providing feedback on the official Arduino BLE libraries throughout the years.
August 27th, 2019 at 20:54:59
Excellent post, thank you very much for sharing!
August 27th, 2019 at 21:31:50
that’s really great news !
so let’s say if one “Nano 33 BLE” can act as a “central” role,
how many other “Nano 33 BLE’s” (acting as peripherals) can it connect to ?
so I would like to have a kind of simple Star-Network topology created out of many “Nano 33 BLE” Boards.
Do you think this library or maybe another one can do BLE-mesh topology (on the “Nano 33 BLE” Board) as well in future ?
October 6th, 2019 at 10:28:13
A central can connect to 3 peripherals simultaneously. Of course you should be able to connect & disconnect from peripherals at will In which case there would be no limit within the above restriction
March 11th, 2020 at 16:31:04
Any updates or new plans for allowing more simultaneously connections to peripherals?
I used nrf52840 and nina b306 with NRF Tools, Softdevice 140 and could connect 8 in default setup and even 16 after some easy changes.. made no problems (only allowing a little less ram for the application)
nrf52840 and nina306 therefore supports up to 20 peripherals as a central!