BLE Central examples for nRF51

[netkruzer]

I see that nRF51 chips support Central and Peripheral modes in SoftDevice 130 v2.0.1 but I don't see any examples for a Central/Master BLE device that can connect to other nRF51 or nRF52 chips.

Does anyone have an example for BLE Central to scan and connect to other devices?

[S3ler]

I am very interested in such an example, too.
Unfortunately I could not find any arduino-BLECentral library or similiar.
But:

All the relevant Nordic SoftDevice (S110, S130, S132) header files are included build path when a SoftDevice is selected

So it should be possible to use one of Nordic Semiconductor's central device examples as a starting point.

[netkruzer]

Are you just able to run Nordic examples directly from the Arduino IDE without​ modification?

I need to give that a try.

[S3ler]

Today I tried to run the Nordic example directly from the Arduino IDE and my result is:
Runs without modification? Clearly not! The examples use a lot of files from Nordic's SDK not included in the core/nRF5/SDK/components/softdevice/s130/headers folder. I even tried to build my own Arduino library including these files, but I could not make it work.

Now I am trying to build a Simple BLE Scanner example based on the Heart Rate Monitor example from the nRF5 SDK 12.3.0

I will update my comment when I have new results.

Update: The problem seems to remain the same - you somehow have to include most of the Nordic's SDK files. Maybe it is easier to use RedBearLab's Central Device example for their RedBear Nanos or arduino-BLEPeriphal as a starting point for solution.

The RedBearLab's project contains a lot of Nordic's SDK and uses SoftDevice S130.

[dlabun]

As far as I know Sandeep has not built a Central / Master version of his BLE library. This core is really only intended to get the basic features like SPI and I2C working, the Bluetooth master or ANT capabilities still require you to build your own library.

[S3ler]

Ok, i tried to insert Nordic's SDK into the sandeepmistry/arduino-nRF5 repository.

But now I am really stuck, I get the compilation error:

In file included from ~/.arduino15/packages/sandeepmistry/hardware/nRF5/0.3.0/cores/nRF5/SDK/components/libraries/atomic_fifo/app_atfifo.c:41:0:
~/.arduino15/packages/sandeepmistry/hardware/nRF5/0.3.0/cores/nRF5/SDK/components/libraries/atomic_fifo/app_atfifo_internal.h:61:9: note: #pragma message: value of __CORTEX_M: (0x00U)
 #pragma message "value of __CORTEX_M: " STR(__CORTEX_M)
         ^
~/.arduino15/packages/sandeepmistry/hardware/nRF5/0.3.0/cores/nRF5/SDK/components/libraries/atomic_fifo/app_atfifo_internal.h:62:2: error: #error Unsupported core version
 #error Unsupported core version
  ^
exit status 1

There are multiple checks like this:

#if ((__CORTEX_M >= 0x03U) || (__CORTEX_SC >= 300U)) == 0
#error Unsupported core version
#endif

But I do not have a clue how to improve the __CORTEX_M value. I am sure it is related with the gcc-arm-none-eabi toolchain an the -mcpu=cortex-m0 compile flag.

Update: Ok the big problem is: all files on the SDK/components are included and build. Many of these files are not needed and not buildable without proper definitions and the right file includes.
My solution including everything tries to build the source-files which are only for the nRF52 too.
This creates too many compilation error.

[dlabun]

This core is using an older version of the Nordic SDK, it's either 9 or 10... I am not 100% of the version but it's definitely not compatible with SDK v12.

[sandeepmistry]

This should be possible with the older S130/S132 SoftDevice. There's some discussion on scanning here sandeepmistry/arduino-BLEPeripheral#155 with @floe.

It would be nicer to see a NordicBLE library made that has the same API as the Arduino 101's CurieBLE: https://github.com/01org/corelibs-arduino101/tree/master/libraries/CurieBLE

[S3ler]

I have now an overview over the Nordic SDK and used Eclipse CDT including a ST-Link V2 to program my Waveshare BLE400 board.
@dlabun Can we move to Nordic SDK version 12.3.0? This includes Softdevice S130 and is the last Nordic SDK version supporting nRF51822 (see release notes), so there should not be further core migrations in the future?
@sandeepmistry Thank you for these links i will take a deeper look into them, especially the CureBLE API. Would you be ok with adding Nordic's SDK into the project (directly within git or via post install download script)?
If yes: I can think of writing a wrapper around Nordic's SDK with the same API as CurieBLE.

Give me your opinions on my idea.

[sandeepmistry]

@S3ler

Can we move to Nordic SDK version 12.3.0? This includes Softdevice S130 and is the last Nordic SDK version supporting nRF51822 (see release notes), so there should not be further core migrations in the future?

Please submit a pull request to do so.

Would you be ok with adding Nordic's SDK into the project (directly within git or via post install download script)?

I don't think it is really needed, plus it has a non-open source license.

[dmikhalsky]

CentralRole support was added in arduino.org's fork of the library
https://github.com/arduino-org/arduino-core-nrf52/blob/master/libraries/BLE/examples/Central/

[kriswiner]

Is someone planning to add the BLECentral component to Mistry's Arduino core so that we can use it just like we use BLEPeripheral? Not sure how to do this myself. Or maybe this is straightforward to use as is. I tried but had a lot of compile errors, etc. just from the fact I have no idea what I am doing.

Anyway, I would love to be able to use the central role examples in the Primo version of the nRF52 core with the core reposited here (which works for my custom nRF52 boards) if some knowledgeable person could explain how to do so. Thanks.

[dmikhalsky]

I am totally with you on that. I tried many different approaches but nothing worked so it seems some cde alterations are needed.
As I can see. Primo's fork relies heavily on Nordic SDK

[dlabun]

There was a pretty big discussion about this months ago (last year maybe?) and it was decided not to add BLE support directly to the core. Personally, I am not working on anything BLE related because I am working with the ANT related features.

[dmikhalsky]

Will ANT implementation include Central role or whatever it's called in ANT specification?