Martin Cowen ⁽³²⁾

Segger Embedded Studio project files appear to be XML formatted with a custom DOCTYPE. <!DOCTYPE CrossStudio_Project_File> <solution Name="ble_app_MA_lightbulb_pca10040_s132" target="8" version="2"> <project Name="ble_app_MA_lightbulb_pca10040_s132"> <configuration Name="Common" arm_architecture="v7EM" arm_core_type="Cortex-M4" arm_endian="Little" arm_fp_abi="Hard" arm_fpu_type="FPv4-SP-D16" arm_linker_heap_size="8192" arm_linker_process_stack_size="0" arm_linker_stack_size="8192" arm_linker_treat_warnings_as_errors="No" ... /> <configuration Name="Debug" c_preprocessor_definitions="DEBUG; DEBUG_NRF" gcc_optimization_level="None" /> </solution>ReadingIn VB.NET, Private xmlDoc As XmlDocument = New XmlDocument()xmlDoc.PreserveWhitespace = TruexmlDoc.XmlResolver = NothingxmlDoc.Load(filename)Once the XML is loaded, an attribute such as c_user_include_directories can be read using this syntax sIncludes = xmlDoc.SelectSingleNode("solution/project/configuration[@c_user_include_directories]").Attributes("c_user_include_directories").ValueWritingHowever, writing out an this XML document object back to a file has a few problems. The DOCTYPE tag changes in that additional square brackets [] appear at the end due to a bug in the .NET framework, so you get <!DOCTYPE CrossStudio_Project_File []> which although is valid XML, causes SES to say that the file is not a valid project. The workaround is to create a new XML Document object and replace the Document Type with a new one, with Nothing (in VB.NET, equivalent to null in C#) for the subset object, as distinct from an empty string. Dim n As XmlDocument = New XmlDocument()n = xmlDoc.Clone()Dim parent As XmlNode = n.DocumentType.ParentNode'4th param in CreateDocumentType has to be Nothing to avoid getting [] in DOCTYPE, which is what…

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…

Apple have just announced their latest 4.7" iPhone. Confusingly they are calling it the iPhone SE, even though they already had an iPhone SE which was a 4" screen. I'm looking at it as an upgrade to the iPhone 6s 128 GB from September 2015, so the comparison only covers that screen size. Most of the data in this chart is from Apple's comparison page. CPU and battery specs are from the relevant Wikipedia pages. The historical UK pricing at launch was obtained from the Guardian. DXO Mark and Geekbench scores are from their own sites. Bold text is used for improvements. Since the iPhone 8 did not launch with a 128 GB option, the choice would have been the 256 GB option at £849 so the iPhone SE (2nd gen) at 128GB at £469 looks like a good deal. Added confirmed DXOMark, RAM and CPU for SE (2nd). Added iPhone 12 mini