Usually I do *not* use floating point numbers in my projects. For this, I select ‘None’ during the project creation in CodeWarrior for MCU:
No Floating Point Selected
But what if I need to change my mind later? How to change such a ‘no-floating-point-needed’ project to one with floating point format support?
Bootloaders are a very useful thing: it allows programming an application file without a debugger. This makes it ideal for upgrading a system in the field.
Usually, there are application notes and examples from silicon vendors available. But typically they are for a certain microcontroller, and hard to change it to another system without a lot knowledge about its implementation. What I need for a project based on the FRDM-KL25Z is a bootloader which shall be small and portable. As I’m using Processor Expert to keep my applications portable across different microcontroller families: why not create a bootloader with Processor Expert components? With the Processor Expert drivers available, things can get a lot simpler compared to the ‘traditional’ approach. With less than 10 KByte footprint?
Serial Bootloader made with Processor Expert
Good news for everyone owning the FRDM-K20D50M board: I have extended the FSL_USB_Stack with USB CDC device class support for the K20D50M :-).
USB CDC Test Application with the FRDM-K20D50M
In this tutorial I explored how to use printf(), and this tutorial is so generic that it works for any processor/microcontroller. That flexibility is because I’m using Processor Expert. In case Processor Expert shall not be used, then some tweaks are needed. Here I show what is needed to have printf() working with the FRDM-KL25Z board. I use the UART0 connected to OpenSDA USB CDC for this.
Freescale/Farnell/Element14 announced last week a new Freedom Board: the FRDM-K20D50M :-). As you can expect, I was not able to resist, and ordered one from my local Farnell store right away. So I did my first steps with it on this sunny and wonderful weekend (yes! we skipped Spring Time and entered Summer Time right away!).
I do not need to compare the board with the previous Freedom boards, as I have found an article here. I a nutshell: I get pretty much the same as with the FRDM-KL25Z, but instead of an ARM Cortex-M0+, it has an ARM Cortex-M4!
The new FRDM-K20D50M Board
In “Tutorial: Accelerating the KL25Z Freedom Board” I used the MMA8451Q accelerometer on the FRDM-KL25Z board in a very primitive way: I’m reading directly some low-level registers from the device through an I2C low-level component. No calibrating, no special device feature setting, only raw values. Since then, things have been evolved: In “Tutorial: Creating a Processor Expert Component for an Accelerometer” I started to create a driver for this accelerometer, and since then a lot more functionality has been added.
Traced Accelerometer Values to the Shell
Many times I have Processor Expert components carefully configured in one project, and then I want to have the same thing in another project. There is actually an easy way to carry out this: to copy components from one project to another.
The maze solving robot based on the Freedom FRDM-KL25Z and Pololu Zumo shield has new features:
FRDM-KL25Z Robot on Practice Area
The FRDM-KL25Z Open Source Logic Analyzer based on SUMP presented here was already very useful with the added trigger support. But it was not capable to do a sampling rate above a few hundred kHz. That’s ok for slower probing, but not for anything with a higher speed. Using DMA (Direct Memory Access) instead of timer based sampling can remove that limitation :-).
FRDM-KL25Z used as Logic Analyzer on another FRDM-KL25Z board
If I want a C++ project for my KL25Z Freedom board, I select C++ during the project creation:
C++ Project Creation for GCC
This creates a gcc C++ project with all the needed settings.
This worked fine until I added a *.c file to my project which had code in it which was not accepted by the C++ compiler. Wait! Should the *.c not be compiled in C mode, as I was used to with other compilers? It turned out that things are different with gcc (or g++) :-(: the *.c files in my project are compiled in C++ mode. So the question is: how to compile in C mode with the ARM g++ compiler?
