Category Archives: Debugging

KL25Z and I2C: Missing Repeated Start Condition

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I really hate this kind of stuff: I know it should work, but it does not. I’m loosing a lot of time (hours, days, even weeks) to track it down to the root cause. Yes, I create my own bugs. Yes, there are bugs in tools, sources, libraries and components. But what many might not believe: there are bugs in silicon too :-(. If you do not believe, here is one: there is a hardware I2C problem on the KL25Z used on the Freedom board. It worked in one project, but not in another.

❗ The silicon bug described here is present on many Kinetis devices, not only the KL25Z!

Logic Analyzer attached to the FRDM-KL25Z board

Logic Analyzer attached to the FRDM-KL25Z board

So if you are facing a problem where you read 0xFF or wrong values from the I2C bus with the KL25Z, here is probably why (and how to workaround it). The problem showed up with a modified version of the Freedom Accelerometer tutorial….

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SWD Debugging with the FRDM-KL25Z Board

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The OpenSDA on the FRDM-KL25Z board is a cool feature: I do not need any external debugging device to program and debug my board :-). But my KL25Z custom board will not have that OpenSDA on it: first because it would add additional costs, and I do not see a way how I could use it for my board. I better start using a SWD/JTAG debugger for my Freedom board to have everything in place.

What I need to add to the black Freedom board is the SWD header:

SWD J6 (populated) and J11 (unpopulated)

SWD J6 (populated) and J11 (unpopulated)

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How (not) to Secure my Microcontroller

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There are several reports in the Freescale forums around having ‘secured’ the Freedom board. But what does ‘securing’ a board mean? And what does it mean if I get that ‘Device is Secure’ dialog?

Device is Secure. Erase to unsecure?

Device is Secure. Erase to unsecure?

There are different levels of protection you can find in many embedded microprocessors, and the terms might vary from vendor to vendor:

  1. Protect
  2. Secure
  3. Disable Mass Erase

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Speeding up the Debug Launch in CodeWarrior

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Whenever I do a debug launch in the Eclipse based CodeWarrior, it takes some time until actually I’m ready to step through my code on the target. Yes, a good part of that is by Eclipse. But another part is that Eclipse helps me to do stupid things (which is a good thing). But say if I know what I’m doing, I could remove some of that safety belts and still doing fine. But only if I know what I’m doing.

A good indicator where Eclipse is spending time is to have a look in the Progress View:

Progress information during launch

Progress information during launch

It shows an interesting information: ‘Build before Launch’….

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Copy my CodeWarrior Project

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I have a project working, and then I want to do a copy. Unfortunately, this is not as simple as it should be :-(. In order to copy a project with all the settings, some knowledge about the internals of the project structure is required, which is the topic of this post.

In “Copy my Project” I was using a ColdFire V2 project which is not an easy case, as is using a Target Task to flash the microcontroller. Fortunately, all other targets in CodeWarrior for MCU are *not* using target tasks :-). With little help and preparation, a copy a project is not that difficult to do.  I’m showing how to do this with the FRDM-KL25Z project I have created in this post.

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Hot-Sync: Attach, Connect & Download

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Usually I compile my sources, link it and pass it to the debugger for downloading it to the target. And ‘downloading’ means for me: flashing to the target (RAM debugging is something for the non-hardcore programmers ;-)). But there are more options than only downloading and flashing. There is definitely more which helps me to do post-mortem (yes, I *love* Latin :cool:) debugging.

Downloading means to me that the debugger will program my application into the device, then loads the symbolics (debug information, source file information, …) and then I debug my application. Looking at the ‘Debug As’ options, there is as well Attach and Connect:

Debug as Attach, Connect and Download

Debug as Attach, Connect and Download

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OpenSDA on the Freedom KL25Z Board

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P&E has released information and firmware instructions for using the OpenSDA, see pemicro.com/opensda. Future has posted a very useful article about using OpenSDA here. So time to upgrade OpenSDA bootloader and firmware v10.1. My FRDM-KL25Z board is a pre-production board, and I assume the production boards expected next week will have the new firmware on it. But it is always useful to know how to change/upgrade the firmware, as I expect there will be new versions of it in the future.

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Eclipse Debugging with Strings – Part 2

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Maybe a better title for this post would be “Eclipse Debugging with Strings Attached’? Digging a bit more into the domain of string debugging, things are not always the way I wish they are.

I’m using here CodeWarrior for MCU10.2, which is based on Eclipse 3.6. Let’s use the following piece of code with the ARM Cortex-M4 Kinetis K60 core and the Freescale ARM compiler:

char buf[] = "abcd";
char *p = &buf[0];

unsigned char ubuf[]="ABCD";
unsigned char *up = &ubuf[0];

signed char sbuf[]="1234";
signed char *sp = &sbuf[0];

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