Bluetooth ⁽⁸⁾

Having got the BLE Lightbulb peripheral example working as I wanted it to on the nRF52 development kit (PCA10040), the next step was to get my other dev kit to be the controller for it, in place of the smartphone app. NovelBits helpfully provides all the code for this on the page How to build the simplest nRF52 BLE Central (Lightbulb use case) but it is targeted at the nRF52840 and SDK 15. I only had one nRF52 dev kit and one nRF51 dev kit. As I learned previously, the nRF51 is only supported by SDK version 12, so I had the job of porting the example code down from SDK version 15 and changing it over to the smaller, M0 based chip. At the same time, the Softdevice (BTLE stack) changes from s132 to s130. My plan was to proceed cautiously, having seen the problems previously in attempting to make many changes in one step and ending up with an uncompilable codebase. As soon as you copy the project folder into the same location in the SDK 12 folder and run my SES Include File Manager, you see that of the 133 include paths 29 are not found,…

SES Include File ManagerA simple helper application for use with Segger Embedded Studio when working with the Nordic Semiconductor SDK. The application checks which paths exist and allows you to remove those that don’t, allows a search by filename to show which folder they are in, and allows conversion between relative and absolute paths for the include folders. (It does not search your SDK folder for include files to automatically add them to the include paths.) The Nordic SDK folder is structured so that many include files which are needed for a project are in different folders. All of the folder paths need to be added to the c_user_include_directories definition for the project to compile. It is time consuming to search for each include file that a compile will complain about being missing so that it’s path can be added to the project c_user_include_directories. It is easy to end up with duplicate paths and unnecessary paths. The relative path can be tricky to manage due to its change of depth (number of ../) when a project is moved within the folder structure. Opens the file, parses it and shows the results in two lists - Include Paths and Include Files.

In the previous post on using a BLE peripheral example, the LED2 could only be controlled in terms of two states, On and Off. With my background of lighting controls, I wasn't satisfied that this could be called a BLE lightbulb project without at least brightness control. Since the example BLE code is already set up to send a byte as the BLE characteristic value, it should be easy to expand the example to brightness control in percentage terms using the byte in the range 0 to 100. The main addition to the previous project is the PWM software module which sets up and controls the internal PWM hardware peripheral on the nRF52832. It is better to use an existing software module which encodes all the knowledge necessary to set up the PWM peripheral rather than just accessing the registers directly which would mean careful study of the datasheet with possible misinterpretation and that gives us an interface layer for future portability. The first location I tried looking for a reference example was SDK\examples\peripheral\led_softblink but it was not suitable for a couple of reasons. led_softblink uses a low power technique for the PWM which involves setting up the PWM timer and…

If you are developing a BLE application with Nordic Semi's SDK, there is a need to generate a UUID for your custom services and characteristics, for example, NovelBits MIDI example. Mohammad Afaneh gives the rules for these UUIDs and suggests using a general purpose UUID generator followed by a manual check for clashes with the BT SIG reserved range. The Nordic SDK method of declaring these UUIDs requires them to be given as byte arrays in reverse order, with least significant byte first. Although this is not difficult to do manually, there is some possibility of error which would be difficult to detect without going through the full debug cycle of programming a device and reading back the UUIDs on a tool such as LightBlue or nRF Connect. I have automated the whole process in a simple Windows Form app - BLE UUID Generator The program generates a UUID immediately when opened, using the built-in Windows GUID functionality. This is checked for collision with the BT SIG reserved range XXXXXXXX-0000-1000-8000-00805F9B34FB and then displayed in the text box as a snippet of C code - as a comment and as a reversed order byte array as required by the Nordic SDK. It…

I was getting a little frustrated with the Nordic examples and tutorials all being not quite ready for use. Not as badly frustrated as this guy but there always seemed to be some mismatch between what was required and what I was using, even when I chose the preferred tools. OK, I made a mistake assuming that I should start with the nRF51-DK because that is a smaller, simpler, cheaper chip. Although when you look into pricing, you find that nRF51's are not necessarily cheaper So I got myself onto the nRF52-DK so that I could use the latest SDK 16 and the Segger SES toolchain, which meets all the requirements in the Getting Starting guide. After going through that, I wanted to find a tutorial that was written from outside Nordic Semi so that it could be more objective about the tools. Given that Mohammad Afaneh is presenting these Ellisys BT videos he seems to be an independent (of Nordic) expert, so his post on How to build the simplest nRF52 BLE Peripheral application (Lightbulb use case) seemed to be a good fit with what I wanted to learn and how to learn it. The rest of this post is my attempt to…