Building a Raspberry Pi UPS and Serial Login Console with tinyK22 (NXP K22FN512)

There are different ways to ruin a Linux system. For the Raspberry Pi which uses a micro SD card as the storage device by default, it comes with two challenges:

  1. Excessive writes to the SD card can wear it out
  2. Sudden power failure during a SD card write can corrupt the file system

For problem one I do I have a mitigation strategy (see “Log2Ram: Extending SD Card Lifetime for Raspberry Pi LoRaWAN Gateway“). Problem two can occur by user error (“you shall not turn it off without a sudo poweroff!”) or with the event of a power outage or black out. So for that problem I wanted to build a UPS for the Raspberry Pi.

Raspberry Pi with UPS System and tinyK22

Raspberry Pi with UPS System and tinyK22

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Tutorial: MCUXpresso SDK with Linux, Part 2: Commandline Debugging with GDB

In “Tutorial: MCUXpresso SDK with Linux, Part 1: Installation and Build with Maked” I used cmake and make to build the SDK application. In this part I’m going to use the command line gdb to debug the application on the board.

Cross-Debugging with GDB

Cross-Debugging with GDB

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Log2Ram: Extending SD Card Lifetime for Raspberry Pi LoRaWAN Gateway

My LoRaWAN gateway (“Contributing an IoT LoRaWAN Raspberry Pi RAK831 Gateway to The Things Network” is running and working great now for more than a month and it already has transmitted more than 30k messages:

Gateway Overview

Gateway Overview

This creates a lot of log entries on the micro SD card of the Raspberry Pi. To avoid writing too many times log data, I have installed Log2Ram.

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Tutorial: RAK813 LoRaWAN+BLE+GPS Sensor Node with Eclipse IDE

In the IoT world, it is all about security, connectivity and low power. LoRaWAN with the Things Network is able to connect devices over several kilometers, and I’m running my gateway for it already (see “Contributing an IoT LoRaWAN Raspberry Pi RAK831 Gateway to The Things Network“). This tutorial is about building a BLE+LoRaWAN+GPS sensor node with GNU tools and Eclipse:

LoRa+BLE with RAK813 and LPC845

LoRa+BLE with RAK813 and LPC845

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Running FreeRTOS on the VEGA RISC-V Board

In “Debugging the RV32M1-VEGA RISC-V with Eclipse and MCUXpresso IDE” I described how to build and debug applications for the VEGA RISC-V board. In this article I describe how to enable FreeRTOS for RISC-V, based on the latest FreeRTOS V10.2.0 release.

Blinky with FreeRTOS on the VEGA RISC-V Board

Blinky with FreeRTOS on the VEGA RISC-V Board

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Contributing an IoT LoRaWAN Raspberry Pi RAK831 Gateway to The Things Network

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.

LoRaWAN TheThingsNetwork Gateway

LoRaWAN TheThingsNetwork Gateway

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Different Ways of Software Configuration

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 tinK22 with OLED LCD

Raspberry Pi and tinyK22 (NXP Kinetis K22FN512) with OLED LCD

How can I deal with this in my application code? Continue reading

Tutorial: HD44780 Display Driver with NXP MCUXpresso SDK

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.

hd44780 display with NXP FRDM-KW41Z Board

hd44780 display with NXP FRDM-KW41Z Board

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FreeRTOS: how to End and Restart the Scheduler

Most host or desktop systems (say Linux, Mac or Windows) have a normal use case where you start the operating system say in the morning and shut it down in the evening, and then you leave the machine. Embedded Systems are different: they are not attended, and they are supposed to run ‘forever’. Not every embedded system needs to run an OS (or in that world: Real-Time Operating System or RTOS), but the same applies here: after the RTOS is started, it is not intended that it will shutdown and restart. To the extend that you won’t they support the ‘shutdown’ and ‘restart’ functionality at all. In case of gathering coverage information this would be really useful:

coverage information from freertos application

coverage information from FreeRTOS application

In the case of FreeRTOS: what if I really need to shutdown the RTOS and restart it again, as by default this is not supported. This is what this article is about …

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Driver and Command Line Shell for Winbond W25Q128 16MByte Serial FLASH Device

Modern microcontroller come with plenty of internal FLASH memory. On the other side, many high performance MCUs as the NXP i.MX RT are ‘flashless’, because the silicon process for high performance cores is not matching the FLASH memory technology, so they are using external serial SPI or Quad-SPI (QSPI) memory instead.

Winbond w25q128 breakout board

Winbond w25q128 Serial Flash Breakout Board

Why not using an external SPI FLASH for a ‘normal’ microcontroller too?

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Driver for VL53L0X Time-Of-Flight (ToF) Sensor and NXP K20DX128

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.

NXP K20dx128 with adafruit vl53l0x tof sensor

NXP K20dx128 with Adafruit VL53LOx tof sensor

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Playing Zork with FreeRTOS on ARM in three different Ways

You might wonder what ‘Zork‘ is? Zork is one of the first and earlist fictive computer games, written around 1977 and 1979, written in MDL on a DEC PDP-10 by members of the MIT Dynamic Modelling group (see https://en.wikipedia.org/wiki/Zork). I believe the first time I have played Zork was around 1984 on a Commodore 64.

Zork

Zork

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Using GDB Server Monitor Commands from Eclipse GDB Console

With Eclipse as IDE it is very easy to debug an application on a board. Still sometimes it is useful to get one level down and control the GDB server directly.

Monitor Flash Download

Monitor Flash Download

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Tutorial: Git with Eclipse

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.

EGit with Eclipse

EGit with Eclipse

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McuOnEclipse Components: 30-Sept-2018 Release

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.

SourceForge

SourceForge

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Tutorial: μCUnit, a Unit Test Framework for Microcontrollers

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.

uCUnit

uCUnit

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Open Source RISC – Eclipse with RISC-V on the SiFive HiFive1 Board

Open Source software has been around for decades. But open source on hardware especially microcontroller is not much a reality these days. But there is something which might change this: RISC-V is a free and open RISC instruction set architecture and for me it has the potential to replace some of the proprietary architectures currently used. RISC-V is not new, but it gets more and more traction in Academia (no surprise).

I wanted to play with RISC-V for over a year, but finally a week ago I did one of these “hey, let’s buy that board” thing again. Sometimes these boards get on a pile to wait a few weeks or longer to get used, but that one I had to try out immediately :-).

SiFive HiFive1 Board

SiFive HiFive1 Board

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Tutorial: Open-Source Embedded GUI Library LittlevGL with i.MX RT1050-EVK

Most embedded projects need an user input device. For the NXP i.MX RT1050-EVK board I have recently added a 480×272 full color touch LCD (see “Adding a Rocktech Capacitive Touch LCD to the NXP i.MX RT1052 EVK“). I have looked at different commercially available GUI libraries, but none of them really were matching my expectations: either very expensive or closed source, or an overkill for small LCDs and projects. But then I have found LittlevGL: free-of-charge, open source, easy to use, well documented and has everything I need. And it really looks gorgeous 🙂

Hello from LittlevGL

Hello from LittlevGL

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Display Library Function Help Text in Eclipse C/C++ Projects

In this short article I show you how to enable one of the hidden gems in Eclipse: how to get a description of the library function used in the code

Library Hover

snprintf() help text

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Using custom FreeRTOS with S32K SDK and OSIF for ARM

In “Tutorial: FreeRTOS 10.0.1 with NXP S32 Design Studio 2018.R1” I showed how to use a custom FreeRTOS with the S32 Design Studio (ARM). The OSIF (OS Interface) provides an operating system and services abstraction for the application which is used by other S32K SDK components:

OSIF in S32K for ARM Eclipse Project

OSIF in S32K for ARM Eclipse Project

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