Unlike other boards from Freescale, the FRDM-KL25Z has no potentiometer or analog components on it. But in many applications an ADC conversion is needed, so here we go with a tutorial reading in an external potentiometer with Eclipse, CodeWarrior and Processor Expert. For this tutorial I have a 10k Ohm linear potentiometer connected to the Freedom board:
Linear potentiometer with the FRDM-KL25Z
With the Zumo I have a base platform for cool robotics applications. So why not build a line following robot with this? Especially as Pololu offers a reflectance sensor array for it. The result is: I have a line following robot 🙂
Line Following ZumoBot
It turned out that things were not working out of the box with the FRDM-KL25Z board. So if you want to do the same thing, here are some tips how to make it working with the Freedom board.
In this post I tapped into how to print messages to a console using the Kinetis/Freedom board. I’m not a fan of printf() for multiple reasons: It is simply a bad thing for embedded systems programming. But as many have asked for it, here is how to say “hello” from the Freedom Board using printf():
Hello World on the Terminal
I think the most important tool for a firmware engineer is a Logic Analyzer. I always have one on my desk. Working in different locations, sometimes I forget to carry it with me. And for sure I would need it. To buy another one to compensate my laziness? Or maybe there is another solution? And here I stumbled over an article about the Logic Sniffer project recently: it is about an open source logic analyzer hardware and firmware project. What a cool idea! Why not using my FRDM-KL25Z Freedom board as a Logic Analyzer? Heck, that would be awesome 🙂
Logic Analyzer with the KL25Z Freedom Board
Maybe Eclipse is ‘too much’, and you are looking for something different? The cool thing with Processor Expert is that while this is Eclipse based, you can use it easily with other tool chains like IAR Embedded Workbench. So you have the choice, and I have explored things a little with porting FreeRTOS for Cortex-M0+ to IAR :-).
IAR Embedded Workbench with FreeRTOS
In this tutorial I’m showing how use IAR with FreeRTOS and the Freedom FRDM-KL25Z Board, using Processor Expert components.
Processor Expert in Eclipse and CodeWarrior is cool thing, and acts as the ‘expert’ for anything around the microcontroller used. But by default, it is acting in the ‘Basic’ level only.
Component Inspector Levels
But there are ways to get it to the Expert level :-).
Some times, especially after making some clock/timing changes in Processor Expert, I have an error showing up in the Processor Expert components:
Processor Expert Components with Errors
Many times Processor Expert is right. But not always: It is possible that Processor Expert is stuck on the error, and there seems no way out. But there is a trick to resolve it….
When I have asked by a student last year if I’m uing Git, I said “Git what?”. Yep, a shame I did not know what Git was a this time. But it is never to late to learn new things.
I was coming from CVS, moved to the successor of it (SVN) and was happy with it. Especially with having a local SVN server and repository, that was (and still is) a great thing. But to truely collaborate with a worldwide community, it is time to use something different: Git.
GitHub Bootcamp: 4 simple steps to git
Question: What makes 8 times ‘beep’, but I cannot hear it?
Answer: My ultrasonic range finder 🙂
FRDM-KL25Z with HC-SR04
What I have added to my FRDM-KL25Z board is an ultrasonic distance sensor, measuring distances up to 4 meters.
Controlling a LED is a great starter for any embedded project: simple and you immediately get feedback if it works :-). Even better: as driving a LED is not different from working with another digital I/O or controlling a solenoid, the ‘LED’ concept and driver is very universal. I recently have simplified my Processor Expert LED component, so it might be a good time to add some more functionality again ;-). Let’s add support for PWM, and adding a shell interface on top of it. That way the LED is dimmable, plus I can do everything with a command interface as well:
LED Properties
MCU on Eclipse 