ARM SWO ITM Console Bidirectional Standard I/O Retargeting

The ARM Cortex M architecture has many features which are underused, probably simply because engineers are not aware of it. SWO (Single Wire Output) is a single trace pin of the ARM Cortex-M CoreSight debug block. trace pin uses the ITM (Instruction Trace Macrocell) on ARM Cortex. It provides a serial output channel, at a high speed higher than the usual UART, because it is clocked at half or a quarter of the core clock frequency, depending on the core and implementation.

As such, it is an ideal high speed output channel to send text or data to the host. This is how it is usually used, but what is unknown to many: it can be used in a bidirectional way with the help of the debugger.

The topic of this article: how to redirect standard I/O like printf() or scanf() using the SWO ITM console: means both sending *and* receiving data over the SWO debug channel: that way I can use it as a kind of UART with a single pin only.

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Controlling an EV Charger with Modbus RTU

The year 2022 is coming to an end, and I have spent some time today on a little side project. It is about making an Electrical Vehicle (EV) wallbox charger accessible over Modbus RTU. It is not finished yet, and I plan to publish more articles on it, but I can share that I’m able to access and control the Heidelberg EV charger with a Raspberry Pi Pico W (Dual Core Cortex M0+), NXP K22FN512 (Cortex M4F) and LPC845 (Single Core Cortex M0+):

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McuOnEclipse Components: 29-Dec-2022 Release

I’m pleased to announce a new release of the McuOnEclipse Processor Expert components, available on SourceForge.

SourceForge

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Fixing “REENT malloc succeeded” Assertion

One little nasty assertion in the GNU standard library appeared a few days ago, kind out of nowhere, reporting “REENT malloc succeeded”:

Obviously it was caused by the call to srand() which sets the ‘seed’ for the standard library (pseudo) random number generator. The assertion happens as well later for calling the rand() function.

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Add extra Storage to the Raspberry Pi Pico with W25Q128 and LittleFS

The RP2040 Pico board comes with 2 MByte onboard FLASH memory. While this is plenty of space for many embedded applications, sometimes it needed to have more storage space. Having the ability to adding an extra SPI FLASH memory with a useful file system comes in handy in such situations. This makes the RP2040 ideal for data logger applications or otherwise store a large amount of data. In this article I’ll show you how to add an extra 16 MByte of memory to the Raspberry Pi Pico board, running FreeRTOS, a command line shell and using LittleFS as the file system.

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Picoprobe: Using the Raspberry Pi Pico as Debug Probe

In Getting Started: Raspberry Pi Pico RP2040 with Eclipse and J-Link I used a SEGGER J-Link EDU for debugging: unfortunately, probably because of silicon shortage, these EDU probes are out of stock everywhere. Luckily, there is a solution: just use another Raspberry Pi Pico!

SWD Debugging with PicoProbe

This turns a $5 Raspberry Pi Pico board in to a very usable and versatile debug probe.

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Tutorial: Creating Bare-bare Embedded Projects with CMake, with Eclipse included

MCU vendors offer SDKs and configuration tools: that’s a good thing, because that way I can get started quickly and get something up and running ideally in a few minutes. But this gets you into a dependency on tools, SDK and configuration tools too: changing later from one MCU to another can be difficult and time consuming. So why not get started with a ‘bare’ project, using general available tools, just with a basic initialization (clocking, startup code, CMSIS), even with the silicon vendor provided IDE and basic support files?

In this case, I show how you easily can do this with CMake, make and Eclipse, without the (direct) need of an SDK.

NXP LPC55S69-EVK with LoRa Shield
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MCUXpresso IDE 11.6.0

With a steady release train, NXP has released last week a new and updated version of their flagship IDE: the version 11.6.0 of the MCUXpresso IDE.

NXP MCUXpresso IDE V11.6.0

And there are several new and cool features with that release, including a power & energy profiler and CMake support.

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Getting Started: Raspberry Pi Pico RP2040 with Eclipse and J-Link

In this time where many micro-controllers have 100+ weeks estimated delivery time, it makes sense to look at alternatives. So it is not a surprise that the Raspberry Pi RP2040 gets used more and more in projects. It is not only inexpensive, it is (at least for now) available which makes all the difference. The RP2040 is the first microcontroller from Raspberry Pi: a dual-core ARM Cortex-M0+ running up to 133 MHz, 264 KByte on-Chip RAM and up to 16 MByte external FLASH.

Raspberry Pi Pico with J-Link, with a NXP sensor board

It is a very versatile microcontroller, with a rich eco-system and set of tools. It can be easily used with C/C++ or MicroPython, and the Raspberry Pi Pico board only costs around $5. There are plenty of tutorials out there, for example how to use the Pico board as debug probe to debug another Pico board. While this is great, there is an easy way to use any existing J-Link and Eclipse IDE too, so this is what this article is about.

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Creating custom Expansion Board and Header for the MCUXpresso Pins Tool

The MCUXpresso Pins Tool is part of the NXP configuration suite which makes pin assignments, configuration and muxing easy. What I have somehow missed from one of the latest updates and releases is that it allows me now to add my own custom headers definition. Not only the tool is now aware of the ‘standard’ Arduino headers, but I can add my own headers too. This can be useful for providers of breakout boards or any kind of board which can be added to a MCU board. In my case it is very useful for projects where we design our own (breadboard-friendly) board or a custom board with an expansion board: we can design a board header and use it in other projects.

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