McuLog: Logging Framework for small Embedded Microcontroller Systems

An essential tool especially developing larger applications or distributed firmware is to use logging. This article presents an open source logging framework I’m using. It is small and easy to use and can log to a console, to a file on the host or even to a file on an embedded file system as FatFS.

Log Output

Log Output

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Tutorial: Adding FreeRTOS to where there is no FreeRTOS

FreeRTOS is pretty much everywhere because it is so simple and universal, and it runs from the smallest to the biggest systems. But it still might be that for the microcontroller device you have selected there is no example or SDK support for it from your vendor of choice. In that case: no problem: I show how you could easily add FreeRTOS plus many more goodies to it.

Binky on NXP LPC845-BRK Board

Binky on NXP LPC845-BRK Board

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FatFS, MinIni, Shell and FreeRTOS for the NXP K22FN512

I’m using the NXP Kinetis K22FN512 in many projects, either with the FRDM-K22F or on the tinyK22: with 120 MHz, 512 KByte FLASH and 128 KByte it has plenty of horsepower for many projects. The other positive thing is that it is supported by the NXP MCUXpresso IDE and SDK. I have now created an example which can be used as base for your own project, featuring FreeRTOS, FatFS, MinIni and a command line shell.

FRDM-K22F with SD Card

FRDM-K22F with SD Card

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FreeRTOS Task Runtime Statistics for NXP i.MX RT1064

FreeRTOS has many cool features, and one is that it can report the CPU percentage spent in each task. The downside is that to get this kind of information some extra work is needed. In this article I show how to do this for the NXP i.MX1064.

FreeRTOS Runtime Information

FreeRTOS Runtime Information

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Tutorial: Rename, Copy or Clone Eclipse Projects with MCUXpresso

Especially in a lab or classroom environment it is convenient to start with a template project, and then explore different ways to shape the project for different needs. As for any IDE of this world, this requires an understanding of the inner workings to get it right. So in this article I show how to copy, clone or rename properly an Eclipse ‘template’ project in the MCUXpresso IDE.

Template Project

Template Project

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Copyright Law for Makers and Educators

Maker spaces and ‘FabLabs’ are popular and accessible in many areas. 3D printers are on the cheap, and powerful laser cutters are in the range of the fearless hobbyist. You can get dirty-cheap PCBs from China in less than a week (ok, probably not right now because of Corona virus) and it is easy to SMD solder parts these days with a DIY SMD PnP machine and OpenPnP. With the right equipment and skill set it is possible to build many cool projects. It is very rewarding and a great learning thing. Blog about it so other can learn too. And it even could get featured on Hackaday.

But: The risk is that someone might send you letter about a ‘Copyright Infringement’. Sadly, this is what happened to me for one of my recent projects. I don’t think that ‘take down’ letter was justified, but I learned a great deal what I should have done differently to avoid that situation. So in the end, it was a learning opportunity, which I believe is worth to share. In essence: what can a maker or educator do?

hackaday building a giant meta-clock made of smaller clocks

Hackaday: building a giant meta-clock made of smaller clocks (image: original image from Hackaday)

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Tutorial: Maximum Clock Frequency for Kinetis using MCUXpresso Clock Tools

The tinyK22 board with the NXP K22FN512 is a bread-board-friendly small board with a 8 MHz external oscillator:

tinyK22 Board

tinyK22 Board

This tutorial is about how to use the NXP MCUXpresso Clock configuration and configure the board to the maximum clock frequency of 120 MHz. The same steps apply to many other boards, including the FRDM-K22F one.

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Enable Default FreeRTOS Debugging for LinkServer Debug Connections

Most of my projects are using FreeRTOS, and I’m using different Debug Probes (SEGGER, P&E and LinkServer) to debug NXP devices.

The NXP LinkServer debug connection is able to show the RTOS threads in Eclipse/MCUXpresso IDE which is incredibly helpful:

FreeRTOS Thread Aware Debugging with LinkServer Connection

FreeRTOS Thread Aware Debugging with LinkServer Connection

However, by default this is turned off. In this article I show how to turn this on by default.

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Ways to apply Eclipse CDT C/C++ Project Settings

Eclipse with its CDT managed Make system makes it easy to build projects, because it can handle a lot of the background tasks and settings between the project and the build setting. It can get a bit difficult if I want to include a library or other sub-source project for which I have to add extra compiler #define or add extra includes path settings.

Eclipse project settings for incliude paths

Eclipse project settings for include paths

This article show the different ways I have found to make such imports (and exports) easier.

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DIY ‘Meta Clock’ with 24 Analog Clocks

Human since 1982 claims

“Human since 1982 have the copyright to works displaying digital time using a grid arrangement of analog clocks…”

I’m not a lawyer, but without obligations (imho) I have removed the content.

Thanks for understanding,

Erich

OpenPnP Solder Paste Dispensing Video

OpenPnP (see “Building a DIY SMT Pick&Place Machine with OpenPnP and Smoothieboard (NXP LPC1769)“) is a cool open source framework to run Pick&Place machines. I have mentored and supported Tobias Mailänder who extended the PnP machine with the ability to dispense solder past on PCBs. Below a video (courtesy of Tobias Mailänder) which shows the machine in action:

It is still a prototype, but things are working very well.

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World Stepper Clock with NXP LPC845

I really love clocks. I think this is I am living here in Switzerland. Beside of that: clock projects are just fun :-). After I have completed a single clock using stepper motors (see “DIY Stepper Motor Clock with NXP LPC845-BRK“), I wanted to build a special one which is able to show up to four different time zones: Below an example with London (UK), New York (USA), Beijing (China) and Lucerne (Switzerland):

Stepper Clock

Stepper Clock

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JTAG Debugging the ESP32 with FT2232 and OpenOCD

In “Eclipse JTAG Debugging the ESP32 with a SEGGER J-Link”  I used a SEGGER J-Link to debug an ESP32 device with JTAG. I looked at using one of the FTDI FT2232HL development boards which are supported by OpenOCD. The FT2232HL is dual high-speed USB to UART/FIFO device, and similar FTDI devices are used on many boards as UART to USB converters. With OpenOCD these devices can be turned into inexpensive JTAG debug probes. This article shows how to use a $10 FTDI board as JTAG interface to program and debug the Espressif ESP32.

FTDI JTAG Connection

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Linking Bootloader Applications with Eclipse and FreeMarker Scripts

Bootloaders are a fine thing: With this I can load any applications I like. Power comes with some complexity, and a bootloader alone is a complex thing already. But this applies to the application part too: I need to link the application to a certain offset in the memory space so it can be loaded by the bootloader, plus the application typically needs to add some extra information to be used by the bootloader. This article describes how to build a bootloader application with Eclipse (MCUXpresso IDE) using the MCUXpresso SDK.

Build Configuration for Bootloader Application

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Stack Canaries with GCC: Checking for Stack Overflow at Runtime

Stack overflows are probably the number 1 enemy of embedded applications: a call to a a printf() monster likely will use too much stack space, resulting in overwritten memory and crashing applications. But stack memory is limited and expensive on these devices, so you don’t want to spend too much space for it. But for sure not to little too. Or bad things will happen.

The Eclipse based MCUXpresso IDE has a ‘Heap and Stack Usage’ view which can be used to monitor the stack usage and shows that a stack overflow happened:

Heap and Stack Usage

Heap and Stack Usage

But this is using the help of the debugger: how to catch stack overflows at runtime without the need of a debugger? There is an option in the GNU gcc compiler to help with this kind of situation, even if it was not originally intended for something different. Continue reading

Programming the ESP32 with an ARM Cortex-M USB CDC Gateway

The Espressif ESP32 devices are getting everywhere: they are inexpensive, readily available and Espressif IDF environment and build system actually is pretty good and working well for me including Eclipse (see “Building and Flashing ESP32 Applications with Eclipse“). The default way to program an ESP32 is to a) enter UART bootloader by pressing some push buttons and b) flash the application with ESP-IDF using a USB cable.

That works fine if the ESP32 is directly connected to the host PC. But in my case it is is behind an NXP Kinetis K22FX512 ARM Cortex-M4F microcontroller and not directly accessible by the host PC. So I had to find a way how to allow boot loading the ESP32 through the ARM Cortex-M which is the topic of this article.

TTGO ESP32 MICRO-D4 Module

TTGO ESP32 MICRO-D4 Module

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DIY Stepper Motor Clock with NXP LPC845-BRK

This project is about building a stepper motor clock around the NXP LPC845-BRK board. The design is using a combination of 3D printed and laser cut parts and costs below $15.

Stepper Clock Acrylic Face White Hands

Stepper Clock Acrylic Face White Hands

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Building and Flashing ESP32 Applications with Eclipse

The new semester is approaching in a very fast way, and so is the new lecture and lab module ‘Advanced Distributed Systems’ at the Lucerne University. For that module we are going to build a new ‘Sumo’ style robot with WLAN capabilities using the ESP32 chip. It will be a new robot PCB, and below is the current robot (based on NXP K22FX512) with the WLAN module connected to it:

Zumo connected to TTGO ESP32 module

Zumo connected to TTGO ESP32 module

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Restoring Default Firmware on Seeed Arch Mix NXP i.MX RT1052 Board

In my previous article “Debug and Execute Code from FLASH on the Seeed Arch Mix NXP i.MX RT1052 Board” I explained how to take complete control over the board and flash and debug a firmware. Of course this overwrites the one which comes by default shipped on the board. This article is about how to restore or update the original firmware.

Restored Seeed Firmware

Restored Seeed Firmware

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Debug and Execute Code from FLASH on the Seeed Arch Mix NXP i.MX RT1052 Board

In my previous article “Seeed Studio Arch Mix NXP i.MX RT1052 Board” I described how I can use and debug the Seeed Arch Mix Board. But so far I only had things running in RAM. Ultimately I want to use the QSPI FLASH memory on the device with my firmware and running code on it. This article shows how to get from RAM execution to SPI FLASH in-place execution (XiP).

Seeed Arch Mix NXP i.MX RT1052 Board

Seeed Arch Mix NXP i.MX RT1052 Board

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