Category Archives: Kinetis

Bluetooth with the Freedom Board

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I’m working now on a lecture robot project using my Freedom Board. And for this I need a wireless communication. I already have IEEE802.15.4 (SMAC) working, but I wanted to add Bluetooth as a low-cost option. I have found an inexpensive Bluetooth module which is available for only around $4-8 which we use in another university class project. The module is an AT command module: that means the microcontroller communicates with AT serial commands with the module, and the Bluetooth stack itself runs on the module. In a minimal configuration I only need 3.3V, GND, TX and RX plus a CMD (Command) pin:

Bluetooth Module

Bluetooth Module

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Tutorial: Using the ARM CMSIS Library

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One of the great advantage of using an ARM core as on my FRDM-KL25Z board is that I can leverage a lot of things from the community. And one big thing around ARM is CMSIS (Cortex Microcontroller Software Interface Standard). It is an industry wide software library for the ARM Cortex microcontroller. Using the CMSIS libraries and interfaces will make it easier to port applications within the ARM Cortex family.

CMSIS Version 3 Block Diagram (Source: Arm.com)

CMSIS Version 3 Block Diagram (Source: Arm.com)

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Creating and using Libraries with ARM gcc and Eclipse

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In ‘A Library with ARM gcc and Eclipse’ I was using the CodeWarrior MCU10.3 beta version to create a library project. At that time I had to do things manually. Now with the final MCU10.3 there is an option in the New Project Wizard which makes things easier:

Library Creation

Library Creation

This will create a library (or better: an archive) with gcc for me. But how to use it from another project?

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Tutorial: ADC with the Freedom Board

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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

Linear potentiometer with the FRDM-KL25Z

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Zumo Line Following with FRDM-KL25Z

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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

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.

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Tutorial: Printf() with (and without) Processor Expert

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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

Hello World on the Terminal

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Turning the Freedom Board into a Logic Analyzer

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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 🙂

I2C Capture with Decoder

Logic Analyzer with the KL25Z Freedom Board

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Tutorial: IAR + FreeRTOS + Freedom Board

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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

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.

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First Steps with Avnet’s Wi-Go Board

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It is already two weeks into 2013, and not to late to mention Christmas: I have received another gift :-). It did not make it for Christmas itself: Because of the overloaded postal service and because the Swiss customs wanted to deeply inspect the board (they probably wanted to try the board too 😉 ). So it had it finally in my hands last week: The Avnet Wi-Go Board:

Avnet Wi-Go Board

Avnet Wi-Go Board

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Debugging ARM Cortex-M0+ Hard Fault with MTB Trace

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And here it is again: a Hard Fault exception raised by the ARM Cortex-M0+ on my Freedom board:

Hard Fault in Debug View

Hard Fault in Debug View

A reason for hard faults are for example dereferencing a NULL pointer. The issue with the ARM Cortex hard fault exception stack is: it is not easy to find out where in the code the problem is.I have created a Processor Expert component to help me to find the location of such an exception. With the Eclipse based CodeWarrior for MCU10.3 there is another way: Trace with the MTB (Micro Trace Buffer)!

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