It is great if vendors provide a starting point for my own projects. A working ‘blinky’ is always a great starter. Convenience always has a price, and with a ‘blinky’ it is that the code size for just ‘toggling a GPIO pin’ is exaggerated. For a device with a tiny amount of RAM and FLASH this can be concerning: will my application ever fit to that device if a ‘blinky’ takes that much? Don’t worry: a blinky (or any other project) can be easily trimmed down.
Binky on NXP LPC845-BRK Board
I use a ‘blinky’ project here just as an example: the trimming tips can apply to any other kind of projects too.
The NXP LPC845-BRK board is a tiny an inexpensive (sub $6) breakout board. The board includes a CMSIS-DAP (LPC11U35) on-board debug probe which can be used as a debug probe to debug any NXP LPC, Kinetis or i.MX RT device 🙂
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
The Teensy boards are great, but as they are they are not really useful for real development, as they lack proper SWD debugging. In “Modifying the Teensy 3.5 and 3.6 for ARM SWD Debugging” I have found a way to get SWD debugging working, at that time with Kinetis Design Studio and the Segger J-Link. This article is about how debug the Teensy with free MCUXpresso IDE and the $20 NXP LPC-Link2 debug probe:
The NXP Freedom boards are very popular. Many of them are inexpensive (less than $20), include a debug interface and can be easily extended with extra shields or boards. Especially the FRDM-KL25Z is very popular: I’m getting told because of Processor Expert and tutorials available on web sites like this one ;-).
Unfortunately there are no small or breadboard friendly Kinetis boards available. There is the NXP LPC800-DIP but with no onboard debugger and without Processor Expert support. We have the tinyK20, but projects tend to use more CPU power, FLASH and RAM space than what the tinyK20 board (50 MHz, 128 KByte FLASH, 16 KByte RAM) can provide. So we ended up designing the big brother of the first tinyK20: the tinyK22 with 120 MHz, 512 KByte of FLASH and 128 KByte of RAM.
Kinetis Design Studio by default uses an older version of EmbSysRegView. This article explains how to upgrade to the latest and greatest version 0.2.6. And how it is possible to use the latest NXP update for the 0.2.4 version:
For me, the available software and tools are the primary key decision factor why I select a particular silicon vendor. Without good software and tools, a microcontroller only ‘sand in plastic case’, even if it is the best microcontroller in the world. I do have several probably excellent microcontroller boards, and they are only getting touched by more durst over the months and years.
The concept of Linux (Open Source, broad developer base and broad usage) is a success story. While there is a lot of diversity (and freedom) in the Linux world, Linux is Linux and again Linux :-). And the world has (mostly) standardized on Linux and its variants on the high embedded system side.
“The Linux Foundation Announces Project to Build Real-Time Operating System for Internet of Things Devices. Open source Zephyr™ Project aims to deliver an RTOS; opens call for developers to help advance project for the smallest footprint IoT devices.“
Ζεφυρος (Zephyros) is the Greek good of spring and the west wind. Obviously this inspired the logo for the Zephyr project:
In “ARM Cortex-M, Interrupts and FreeRTOS: Part 1” I started with the ARM Cortex-M interrupt system. Because the ARM implementation cann be very confusing, I confused myself and had to fix and extend the description in Part 1 :-). Thank for all the feedback and comments!
Originally I wanted to cover FreeRTOS in Part 2. Based on the questions and discussions in Part 1 I thought it might be a good idea to provide visual examples.
The ARM Cortex-M microcontroller are very popular. And it has a very flexible and powerful nested vectored interrupt controller (NVIC) on it. But for many, including myself, the Cortex-M interrupt system can be leading to many bugs and lots of frustration :-(.
ARM Cortex-M7: NXP KV58
Understanding the NVIC and the ARM Cortex-M interrupt system is essential for every embedded application, but even for if using an realtime operating system: if you mess up with interrupts, very bad things will happen….
I’m using Processor Expert components for nearly every Freescale (now NXP) projects: for S08, S12, ColdFire, DSC and especially all the different NXP Kinetis devices. Not only because it makes software development fast and easy and allows re-use of software, but as well because Processor Expert has a good way to pack and distribute software components. Unfortunately Processor Expert is not any more included for the new Kinetis devices (see “First NXP Kinetis SDK Release: SDK V2.0 with Online On-Demand Package Builder“). So I have looked into an alternative and hopefully vendor neutral way to build and distribute software packages using CMSIS-Pack.