Category Archives: CPU’s

Problem: undefined reference to ‘__end__’ if using Semihosting

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In case you are running into the following GNU linker error about a missing __end__:

'Building target: MyProject.elf'
'Invoking: Cross ARM C++ Linker'
...
toolchain/bin/../lib/gcc/arm-none-eabi/4.8.4/../../../../arm-none-eabi/lib/armv6-m/rdimon-crt0.o: In function `_start':
(.text+0xdc): undefined reference to `__end__'
collect2.exe: error: ld returned 1 exit status
make: *** [MyProject.elf] Error 1
Failed link because missing __end__

Failed link because missing __end__

The GNU linker complains that rdimon-crt0.o needs the symbol __end__.  This symbol marks the end of the user data/RAM section, and is needed by the rdimon library specs which is used with semihosting.

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Semihosting for Kinetis Design Studio V3.0.0 and GNU ARM Embedded (launchpad)

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Freescale has released the v3.0.0 version of the Kinetis Design Studio: this one comes with a great positive change: instead of a custom toolchain, it is coming with the standard GNU ARM Embedded (launchpad) toolchain from ARM. Beside of better code density and less RAM needed, there is one change which affects semihosting. Previously, semihosting was enabled by default in the V2.0.0 libraries. Now semihosting needs to be turned on. This post is how to do this.

Semihosting Console with Output in Eclipse

Semihosting Console with Output in Eclipse

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Solving “The connected emulator does not support serial wire output (SWO)” for Segger J-Link

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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)

The connected emulator does not support serial wire output (SWO)

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Debugging the FRDM-K64F with P&E Multilink

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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

FRDM-K64F with P&E Multilink (click to enlarge)

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CRC Checksum Generation with ‘SRecord’ Tools for GNU and Eclipse

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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:

SRecord 1.64 Web Page
SRecord 1.64 Web Page
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Semihosting with GNU ARM Embedded (Launchpad) and Kinetis Design Studio

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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

Semihosting Output in Console

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Proof of Concept: Open Source ARM SWD Debug and General Purpose Board

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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

FRDM-K20D50M used as debug probe

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