SWO (Serial Wire Output) is a cool feature defined by ARM as part of the CoreSight debug block. However, not every debug connection supports SWO, as it requries extra pins routed from the microcontroller to the debug JTAG/SWD header.
If I’m using the Segger J-Link, and if my hardware does not support SWO, I will get a dialog telling me “The connected emulator does not support serial wire output (SWO).”
The connected emulator does not support serial wire output (SWO)
In case you face problems with launching GDB: Then I have a quick solution (well: workaround): kill the GDB server and or client process. The problem can show up in many way, but in general gdb is stuck or does not respond:
GDB stuck?
But it could be an error message like this too:
Error in services launch sequence Starting J-Link GDB Server timed out.
After the proof of concept phase (see “Proof of Concept: Open Source ARM SWD Debug and General Purpose Board“), the first prototypes are ready:
Two tinyK20 Boards
The FRDM-K64F board as other Freescale Freedom board have an onboard debugging device. For everyone who wants to debug the FRDM-K64F board with say a P&E Universal Multilink, here is my setup in case you do not get it working out of the box:
FRDM-K64F with P&E Multilink (click to enlarge)
I very much liked the CodeRed Eclipse based IDE (see “Red Suite 5: Eclipse Juno, Processor Expert and unlimited FRDM-KL25Z“). But back in May 2013 CodeRed was acquired by NXP. I have not used much NXP devices for my projects, and as CodeRed was focusing on the NXP parts, CodeRed was not running daily on my desk any more :-(. Well, things might make a full back circle, as NXP announced back March 1st 2015 to acquire Freescale :-). And maybe as a taste how things might come out, the GNU ARM Eclipse plugin release from March 22nd 2015 includes a CodeRed debug view 🙂 🙂
CodeRed Debug Perspective in KDS
That debug perspective mimics a CodeRed debug perspective. The advantage of this Eclipse perspective is that it works very well with small screens. This post is about adding this perspective to the recently release Kinetis Design Studio v3.0.0.
One of the things missing for Embedded in the GNU linker is that it cannot generate a CRC checksum. Luckily, there is the solution of using SRecord:
A while back I wrote two articles about Semihosting: “Semihosting with GNU ARM Embedded (LaunchPad) and GNU ARM Eclipse Debug Plugins” and Semihosting with Kinetis Design Studio. With using the GNU ARM Embedded (lauchpad) in my Kinetis Design Studio, time for a ‘summary’ post :-).
Semihosting Output in Console
The Teensy is a great and tiny board (see “USB CDC with the Teensy 3.1 Board“), but it lacks real SWD/JTAG debugging capabilities (see “Hacking the Teensy V3.1 for SWD Debugging“). The Freescale Freedom boards are great, but for many applications too big, and have potentially too many components on it. So what about building a breadboard friendly tiny board which *has* SWD debugging ability *and* can be used to debug another boards?
So here is a working prototype based on the FRDM-K20D50M:
FRDM-K20D50M used as debug probe
In my classes I’m mainly using the Freescale FRDM-KL25Z board, as it provides the best value for the money, and 128 kByte FLASH with 16 kByte of RAM is enough for many smaller projects. I do have as well the FRDM-KL02Z Board (32 KByte FLASH, 4 KByte of RAM) which is an inexpensive board to evaluate the smaller KL02Z microcontroller. Because someone reported a problem not being able to use the UART over OpenSDA/USB-to-CDC bridge, I have created a demo project which communicates with a console on the host.
FRDM-KL02Z Board
P&E has upgraded their GDB implementation and interface used in combination with the GNU ARM Eclipse plugins: they support now advanced flash programming options plus the ability to attach/connect to a running target :-). This update is available as Eclipse update.
Advanced Options
MCU on Eclipse 