I’m working with a student on building a small autonomous robot platform, based on the FRDM-KL25Z board. We integrated new software modules, compiled and linked, and then downloaded the application to the board. While debugging and stepping through the application startup, I had this:
The Debugger has lost communication on connection
Outsch! That’s not good. Even worse, trying to connect again to the board failed 
. What happened?
Looks like there is some movement on the ‘OpenSDA Front’: After CodeRed has released their RedProbe OpenSDA firmware, now Segger has released an OpenSDA firmware.
With this, I get a low-cost debugging solution similar to the well-known J-Link run control devices. The OpenSDA Segger Firmware is something like a J-Link-lite.
FRDM-KL25Z with Segger OpenSDA Debug Firmware
If you are following my recent posts, then you know I started using USBDM on OpenSDA as an alternative run control solution. Now with the advent of MCU10.4, the question is: how to use USBDM with it, because the USBDM installer obviously only knows the version up to MCU10.3?
USBDM 4.10.4a Installer
Ok, this one might not work for everyone. And maybe I’m seeing a ghost. But a nice and real one, at least for me 
. It seems that with the new CodeWarrior for MCU10.4 installation I was able to recover a bricked OpenSDA FRDM-KL25Z board 
Recovered OpenSDA Board
Teaching at a university means to work in a very special environment. What students love is ‘Open Source’: because it allows them to ‘see’ things and learn from the technology. The other thing is: students have a low budgets, so they appreciate if they can use inexpensive or low-cost hardware and software. The FRDM-KL25Z Freedom board for sure meets that low price, and no extra programming device needed.
Now they are building their own boards, and they wish to program and debug it. They can borrow the Segger J-Links and P&E Multilinks we have available at the university. But why not use the Freedom board as ‘hobby’ debug and programming solution? As explored in “Using the Freedom Board as SWD Programmer“, they can use the default factory installed OpenSDA to program another microcontroller of same type. But not to debug it.
While writing the ”Using the Freedom Board as SWD Programmer” article, I was looking into USBDM. USBDM has added in January 2013 support for OpenSDA. But at that time, it was somehow not working for me, and I had not enough time to find out what the problem was. Time to get that fixed. Good news: With help and tips from the USBDM community, I have it finally working
USBDM Debugging another FRDM-KL25Z
“As an engineer, you should ask for the best tools available. Spending money for better tools can make the difference between finding a problem quickly, or wasting days or weeks, and ultimately failing a project.” (unknown)
I had to learn it the hard way: some ‘hard-to-find-problems’ sometimes only can be found with some amount of luck, or with using a good trace solution. CodeWarrior already supports trace, such as using the MTB on the Cortex-M0+. But with this I’m limited to the on-chip trace buffer or on-chip RAM, which is better than nothing. But to solve the real hard problems, a bit of more power and memory is needed. And here where the P&E Tracelink comes into play: with 128 MByte trace buffer it would allow me to record a lot more trace data .
Debugging is usually a ‘stop-inspect-continue’ process. That does not work very well for watching a system which continuously changes its state. For this usually I toggle an LED, or write things to the console to watch with a human eye what is going on. But there is something very powerful in the CodeWarrior debugger too: to display variables and memory content while the target is running.
Variable Live View
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, see this forum discussion. I better start using a JTAG debugger for my Freedom board to have everything in place.
What I need to add to the black Freedom board is the JTAG header:
SWD J6 (populated) and J11 (unpopulated)
In ‘Device is Secure‘ I had a case where this was a false alarm. But recently there has been a report in the Freescale Forum that this can be a real problem with the Freedom KL25Z board I’m using too. I was not able to reproduce this on my end, so a reader of this blog who sent me a binary file to reproduce it.
Well, I was really scared to try that ‘killer’ file on my board, but well, that board is not that expensive, and I have 5 pieces of silicon at hand from a sample order . So I took some risk, and programmed that binary using the simple flash programmer. And indeed, when I wanted to debug it again, I got that dialog with my black Freedom board:
Device is Secure. Erase to unsecure?
USB has two sides: if it works, it is great . If it does not, it is really bad . It took a while in the desktop and PC world until USB for common devices (mouse, keyboard, memory sticks, …) was working without issues. But ‘non-standard’ devices like a USB debugging probe/cable are not of that kind of category.
Occasionally I run into USB driver issues in my class. So this post is about identifying the different USB driver parts for the P&E OpenSDA, P&E OSBDM/OSJTAG and P&E Multilinks. And how to install the drivers manually if something is not going well.
