LoRa and LoRaWAN is getting the de-facto wireless IoT network in my area. No surprise that traditional telecom providers like Swisscom trying to monetize the ‘Internet of Things’ area. Luckily there is an open and free alternative: https://www.thethingsnetwork.org/. Volunteers, enthusiasts and members in the different TTN communities build gateways and offer free LoRaWAN network access. I wanted to contribute to that grassroots movement with building my gateway, providing LoRaWAN access to my neighborhood.
Most of the time software needs some way to configure things: depending on the settings, the software will do different things. For example the software running on the microcontroller on top of the Raspberry might have the OLED LCD available or not:
Raspberry Pi and tinyK22 (NXP Kinetis K22FN512) with OLED LCD
Sometimes I start a project with an ARM microcontroller, and in the middle of the project I find out that it was a wrong choice at the beginning and I need to switch the microcontroller derivative or even the used ARM core. With little knowledge of the project structure and the files needed, such a switch is not the easiest thing, but definitely possible.
I really love tiny and bread board friendly boards, especially if they are very affordable and can be use with Eclipse based tools. So I was excited to see the NXP LPC845-BRK board to be available at Mouser, so I ended up ordering multiple boards right away. Why multiple? Because they only cost CHF 5.95 (around $6)!
In the age of high-resolution graphical LCDs using a character display might look like a bit anachronistic. But these displays provide a lot of value for me as they are robust, available in different shapes and number of lines. And such a character display can be a better solution for an industrial application.
GDB supports a mode which allows the GDB debug client to read memory while the target is running. This allows features like ‘live variables’: that way I can see the variables refreshed and changing over time without halting the target. Another functionality which comes with that feature is to check stopped threads or to see all threads in the system.
I’m using the VL6180X ToF (Time-of-Flight) sensors successfully in different projects. The VL6180X is great, but only can measure distances up to 20 cm and in ‘extended mode’ up to 60 cm. For a project I need to go beyond that, so the logical choice is the VL53L0X which measures between 30 cm and 100 cm or up to 200 cm. For this project I’m using the VL53L0X breakout board from Adafruit, but similar products are available e.g. from Pololu.
Working with low power modes can be challenging. It can severely affect debugging capabilities of a microprocessor or microcontroller. I ported a FreeRTOS application using the Tickless Idle Mode to the NXP i.MX RT1064 board, and all of a sudden, the board was unresponsive to any debugger connection. Luckily the board was not really bricked, but it took me while to find a way to recover it. So for when you end up in a situation with a ‘bricked’ i.MX RT1064 board, this article might be helpful for you to recover it.
There are things which are game changer in the world of software development: one such event was when I started using a VCS (Version Control System): it changed for me how I keep and store my projects and settings. It even changed the way how I deal with non-software related items like documents or other valuable things: I started storing them in to a VCS too.
I’m pleased to announce a new release of the McuOnEclipse components, available on SourceForge. This release includes several bug fixes, extra support for the NXP S32 Design Studio and SDK and includes FreeRTOS V10.1.1.
Unit testing is a common practice for host development. But for embedded development this still seems mostly a ‘blank’ area. Mostly because embedded engineers are not used to unit testing, or because the usual framework for unit testing requires too many resources on an embedded target?
What I have used is the μCUnit framework which is a small and easy to use framework, targeting small microcontroller applications.
The McuOnEclipse GitHub repository hosts many Processor Expert projects and is very popular (cloned more than 1000 times, thank you!). Processor Expert is a powerful framework which generates driver and configuration code, simplifying application development for a wide range of microcontroller and families. But Processor Expert won’t be developed further by NXP and is not part of MCUXpresso IDE. While it is possible to install Processor Expert into MCUXpresso IDE 10.2, how can these projects used ini an IDE *without* Processor Expert? This article describes how to port an existing Processor Expert project into the NXP MCUXpresso IDE.
Ported Project with FRDM-K64F using Adafruit SSD1351 and Processor Expert
NXP not only sells general purpose microcontroller, but as well a portfolio of automotive devices which includes the S32K which is ARM Cortex based. For this device family, they offer the S32 Design Studio (or S32DS) with its own Eclipse distribution and SDK. The interesting part is that the S32DS includes Processor Expert (which is a bit different from the ‘mainstream’ Processor Expert). It comes with its own components for the S32K SDK which includes a component for FreeRTOS. But that component in S32DS 2018.R1 comes with an old V8.2.1 FreeRTOS component:
FreeRTOS 8.2.1 in S32DS 2018.R1
So what to do if I want to use the latest FreeRTOS (currently 10.0.1) with all the bells and whistles?
By default, the GNU compiler (gcc) optimizes each compilation unit (source file) separately. This is effective, but misses the opportunity to optimize across compilation units. Here is where the Link Time Optimization (LTO, option -flto) can help out: with a global view it can optimize one step further.
The other positive side effect is that the linker can flag possible issues like the one below which are not visible to the compiler alone:
type of '__SP_INIT' does not match original declaration [enabled by default]