Tag Archives: Debugging

Stack Canaries with GCC: Checking for Stack Overflow at Runtime

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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 →

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Eclipse JTAG Debugging the ESP32 with a SEGGER J-Link

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When Espressif released in 2014 their first WiFi ESP8266 transceiver, they took over at least the hobby market with their inexpensive wireless devices. Yet again, the successor ESP32 device is used in many projects. Rightfully there are many other industrial Wi-Fi solutions, but Espressif opened up the door for Wi-Fi in many low cost projects. Many projects use the ESP devices in an Arduino environment which basically means decent debugging except using printf() style which is … hmmm … better than nothing.

What is maybe not known to many ESP32 users: there *is* actually a way to use JTAG with the ESP32 devices :-). It requires some extra tools and setup, but with I have a decent Eclipse based way to debug the code. And this is what this article is about: how to use a SEGGER J-Link with Eclipse and OpenOCD for JTAG debugging the ESP32.

Roboter with ESP32 and JTAG Debug Port

Robot with ESP32 and JTAG Debug Port

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Tutorial: How to Optimize Code and RAM Size

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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

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.

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

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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

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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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Seeed Studio Arch Mix NXP i.MX RT1052 Board

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The Seeed Studio ‘Arch Mix’ board is a small and versatile development board with an NXP i.MX RT1052 on it, and it costs only $29.90. So I was not able to resist and just have ordered one so I can explore it.

Seeed Arch Mix Top Side

Seeed Arch Mix Top Side

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Visualizing Global Variables while Target is Running with Eclipse and MCUXpresso IDE

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By default, Eclipse provides ‘stop-mode-debugging’: in order to inspect the target code and data, I have to stop the target. But with the right extensions as present in the Eclipse based MCUXpresso IDE, it is possible to inspect the target even while it is running.

Graphing Variables

Graphing Variables

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Black Magic Open Source Debug Probe for ARM with Eclipse and GDB

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The ‘Black Magic Probe’ (or in short: BMP) is a very small and open source JTAG/SWD debug probe with a build-in GDB Server. I saw that probe referenced in different places, so I thought I try it out with a few of my NXP LPC and Kinetis boards:

BMP with LPC and Kinetis Boards

BMP with LPC and Kinetis Boards

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New NXP MCUXpresso Eclipse IDE v11.0

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A few days ago NXP has released a new version of their Eclipse IDE flagship: the MCUXpresso IDE v11.0.

NXP MCUXpresso IDE V11.0.0

NXP MCUXpresso IDE V11.0.0

The previous v10.3.1 was released back in Feb 2019, and the 11.0 now in June this year matches up with the Fall university semester. I appreciate that the releases are about every 6 months, so this gives me time to use it in my university lecture material and lab work. I had the weekend for trying it out, and I’m very pleased.

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SWO with NXP i.MX RT1064-EVK Board

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With the cost of an single pin, many ARM Cortex-M boards including the NXP i.MX RT1064 can produde SWO data: think about a pin able to stream data out of the chip in realtime. For example interrupt activity which otherwise might be hard to capture:

SWO Interrupt Trace

SWO Interrupt Trace

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Reverse Engineering of a Not-so-Secure IoT Device

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The ‘Internet of Things’ is coming! It started as an overused marketing hype with no real use case (who needs internet connected fridges? Who wants the internet connected toilet paper?).

New ‘things’ start to pop up, useful or not: From smart bulbs (Philips Hue), thermostats (Nest), smart TV (Samsung and others) up to voice assistants (Alexa, Cortana, Google). You might even have installed one of these, right? What about temperature and humidity sensors? Probably there is nothing wrong with that?

But what would you think if one morning you find a strange unknown device installed under your working desk, connected to the cloud and internet?

IoT Device attached under a working desk

IoT Device attached under a working desk

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MCUXpresso Eclipse IDE Mouse Tips & Tricks

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In a modern development workflow both command-line and a graphical user interface has its place. On the GUI side, Eclipse is famous that it offers many different ways to accomplish something which is great. But sometimes I continue to use an old habit or way because I have missed that there is a newer and better way, and the MCUXpresso Eclipse IDE is no exception to that. In this article I show a few ways how to use the mouse even more productive.

Project Settings

Project Settings

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Internal and External Debug Options for the NXP LPC55S69-EVK Board

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The LPC55S69-EVK board comes on-board debug probe. The board includes the LPC4322JET100 device which acts like NXP LPC-Link2 debug probe:

LPC4322JET100 on LPC55S69-EVK

LPC4322JET100 on LPC55S69-EVK

But it is easily possible to use the board with an external debug probe or re-program the onboard one as a SEGGER J-Link debug probe.

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TrustZone with ARMv8-M and the NXP LPC55S69-EVK

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The ARM TrustZone is an optional secu=rity feature for Cortex-M33 which shall improve the security for embedded applications running on microcontroller as the NXP LPC55S69 (dual-core M33) on the LPC55S69-EVK.

NXP LPC55S69-EVK Board

NXP LPC55S69-EVK Board

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First Steps with the LPC55S69-EVK (Dual-Core ARM Cortex-M33 with Trustzone)

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For the long Easter weekend I have organized a new toy: the NXP LPC55S69-EVK board: a dual ARM Cortex-M33 running at 100 MHz with ARM TrustZone:

LPC55S69 Microcontroller

LPC55S69 Microcontroller

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

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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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Be aware: Floating Point Operations on ARM Cortex-M4F

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My mantra is *not* to use any floating point data types in embedded applications, or at least to avoid them whenever possible: for most applications they are not necessary and can be replaced by fixed point operations. Not only floating point operations have numerical problems, they can lead to performance problems as in the following (simplified) example:

#define NOF  64
static uint32_t samples[NOF];
static float Fsamples[NOF];
float fZeroCurrent = 8.0;

static void ProcessSamples(void) {
  int i;

  for (i=0; i<NOF; i++) {
    Fsamples[i] = samples[i]*3.3/4096.0 - fZeroCurrent;
  }
}

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

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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

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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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Debugging the RV32M1-VEGA RISC-V with Eclipse and MCUXpresso IDE

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The ARM Cortex cores are everywhere. I like (and use) them a lot. Don’t take me wrong: maybe ARM needs some competition? It is very refreshing to see that something new is getting a lot of attention: RISC-V!

RV32M1

RV32M1 (VEGA)

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