The good thing with the internet is: it allows engineers to collaborate. And here is an example: Marc is a reader of this blog had a problem with the I2C hardware of a Freescale Kinetis ARM microcontroller. In his case, the I2C bus could be stuck, and there seems no way to reset it with the I2C hardware on the microcontroller. So a solution would be to reset it with software instead.
I was searching the internet for an open source network stack for my nRF24L01+ transceivers. But these stacks were either too heavy or had a restrictive or not really non-open source license behind it. I was very reluctant to start with something I think already should exist. Two weeks ago I decided that I just do it from scratch, and here I am: I have the basics working
In case you are desperately looking a component in the components library view, but somehow it does not show up? For example I know there is component ‘InterruptVector’, but it is not present in the Components library view?
So this tutorial is about using a terminal connection between my board and my host (e.g. a notebook) to read and write text:
Yes, I have been busy with all the different ARM Cortex Mx cores I’m using in my projects. But beside of the ‘ARM domination of the world’, there are other interesting processors out there. While the ARM cores have added DSP (Digital Signal Processing) capabilities blurring the boundaries between pure MCU and DSP processors, there is still a place (or niche?) for specialized DSP processors. The power of such processors is in the domain of fast signal processing, e.g. for intelligent power switches or for advanced motor control.
For the Eclipse and Processor Expert lovers of this world: there is another Eclipse based IDE you can use: ThunderBench made by Emprog:
They support a range of ARM based devices, including the Freescale ones I’m using. So I downloaded the v3.24 30 day trial from their download page last week. Finally I have found some time to try it out. Could this be an alternative to use my Freescale FRDM boards with Processor Expert?
This week I saw on the IAR website that they have released the new IAR Embedded Workbench v6.7 for ARM. I was still on 6.5 using the free code size limited ‘Kickstart’ version), so I thought it would be a good time to upgrade to the v6.7. And there are good reasons as the connection to Processor Expert makes things much easier now.
CodeWarrior for MCU10.5 comes with a new Eclipse and new Processor Expert. Things are working very well so far. But I have spotted an issue which seems to be related to the new Eclipse Juno used: sometimes the Processor Expert ‘Components’ view is not correctly showing the current project used.
If you were wondering why I am pushing the FRDM-KL25Z boards hard to the micro-amps, then have a look at this:
The five boards are the first set of prototypes with a FRDM-KL25Z for a battery operated wireless sensor network based on the nRF24L01+ 2.4GHz transceiver.
If you read my posts, then you probably know: I *love* the FRDM boards! But: Freescale has only the lower-end processors available with a FRDM board (yet?). As I need something more powerful for my Raspberry Pi Camera project, I’m using Tower boards instead. This gives me an ARM Cortex-M4 with 120 MHz, Floating Point unit plus 128 KByte SRAM :-).
For that project I need USB. So this post is about using the TWR-K60F120M and TWR-K70F120M with USB connectivity, using the USB CDC device class as example. Initially I thought I can do as easily with the FRDM boards. It turned out, that things are not that easy.
Eclipse based IDE’s have typically one limitation: the IDE has not much scripting capabilities. Yes, I can use things like JUnit for testing, but if it comes to build and debug C/C++ applications, then support gets really rare. An exception to this is CodeWarrior for MCU which features a command line version of the IDE which can be used for test automation as I used it in one of my tutorials. What I missed so far is to have a command line interface for Processor Expert to generate code. This is now possible with CodeWarrior for MCU10.5 :-).
The FRDM-KL25Z is a great board: inexpensive (around US$15), small form factor, has easily accessible pins, and has a low power (capable, at least) microcontroller, and comes with an embedded debugging interface. So why not using this board right away ‘as is’ for a low power battery operated device? Great idea, you think? Yes, I thought too. Only to find out that the board needs 20 mA out of the box.
The good news is: It is possible on a week-end to get this 150 times better down to 132 μA, with an RTOS running all the time :-). I invite you to join a journey with board modifications, jumpers, schematics and many multimeter pictures ;-)….
The Eclipse IDE is in my view the best IDE in the world :-). But it is not the fastest one: All the functionality and comfort has a price, and such a Java and highly flexible IDE requires its resources. The Eclipse community is continuously addressing that concern, and for example the Eclipse Juno 4.2 IDE in CodeWarrior for MCU10.5 shows this nicely: things are much smoother compared to the Eclipse Indigo 3.7 in MCU10.4. But if you feel that you do not want to use Processor Expert because it is too slow, then I have a trick how to improve performance by a factor of 10 :-).
Now I have implemented a watchdog with Processor Expert for my system. But what I have found out? I ended up with a looping system, and the watchdog did not fire
What went wrong?
In this semester course, students (and myself too, of course :-)) are building a Mini Sumo Robot. That robot is using the Freescale FRDM-KL25Z board with an ARM Cortex-M0+ on it. Today I’ll give an introduction to the ARM core to the class, and timing is right: this morning I have found an excellent overview about ARM microcontroller and tools written by Jay Carlson.: Getting Started with ARM Microcontrollers.