I finally completed my project turning the FRDM-KL25Z board into a USB mouse device :-). The form factor and the capabilities of the Freedom board makes it a great board for implementing it as a ‘custom mouse’. All what I need is the USB stack running on it and have it acting as USB HID Mouse device.
FRDM-KL25Z enumerated as USB HID Mouse Device
A week ago, the updated FreeRTOS V7.5.0 has been released on FreeRTOS.org. So time to have my Processor Expert FreeRTOS component updated as well :-).
FreeRTOS V7.5.0
This is the third part of a tutorial series how to ‘do-it-yourself’ a tool chain for the Freescale Kinetis microcontroller, with the FRDM-KL25Z as example. The tool chain is using GNU ARM gcc plus Eclipse Kepler release. So far I have the following parts:
So far things are very generic. But with debugging it means different hardware, and different hardware connections. And for this connection we need a GDB Server.
Eclipse CDT features a GNU Debugger (GDB), and this is what I want to use here: debugging my microcontroller with GDB inside Eclipse. In order to debug the microcontroller, I need two other things: a GDB Server and a Debug Probe.
GDB with GDB Server
This is the second part of a multi-part tutorial about how to set up an open source tool chain with GNU ARM gcc + Eclipse to build and debug an application for Kinetis ARM devices.
Eclipse Kepler
This is the first part of a multi-part tutorial on setting up a free and functional GNU gcc + Eclipse + debugger environment for use with the Freescale FRDM-KL25Z board.
In this first part, I’m showing how to install the GNU ARM tool chain to build a ‘blinking LED’ application for the FRDM-KL25Z. With 100% free tools 😉
Blinking Red RGB LED made with free tools
For my embedded systems lecture I need a wireless connection to the robot we will develop during that course. So far I have SMAC (IEEE802.15.4) and Bluetooth worked out. But that IEEE802.15.4 (ZigBee) is expensive, and the cheap Bluetooth modules are great for robot-to-host connection, but not for swarm robots which need to communicate to each other. Alex Vecchio (see this post) pointed me to a $2.75 (!) wireless module featuring the Nordic Semiconductor nRF24L01+. Exactly what I needed, with an incredible low price :-).
nRF24L01+ Module Detail
The Freedom boards FRDM-KL25Z RevE and FRDM-K20D50M make it easier to use it as USB Host device, as they come with a special jumper to provide 5V to the USB device, so my earlier ‘hack’ is not needed any more :-). After I had USB MSD Host working for the FRDM-KL25Z, it was much harder to get the USB stack working for the FRDM-K20D50M board, because somehow the example Freescale provided with their USB stack refused to work properly on my board. After debugging it for several nightly hours, I decided to take my working Processor Expert project for KL25Z and added support for the K20. And the good news is: since tonight this is working :-).
FRDM-K20D50M as USB MSD Host
While working on a project for the FRDM-K20D50M, I faced a problem: I was running out of SRAM for my application. The GNU linker reports: “section `.bss’ will not fit in region `m_data'”: 😦
bss will not fit in region m_data
But my device has 16 KByte of SRAM, and I knew I use much less than 10 KByte. So what is the problem? Continue reading
I was thinking that these common and cheap bluetooth modules have either HC-05 or HC-06 firmware (see this post). Well, I was wrong: there are more! Obviously there many more firmware images available on that British CSR BlueCore4-Ext chip. Mihai Surdeanu contacted me with an updated firmware for a module which has the “BC04” firmware on it. He was so gentle and has sent me an updated Processor Expert component which works with that BC04 firmware :-).
It took me a while to find the time to upgrade to FreeRTOS V7.4.2, but finally it is done :-). What caused me to move from V7.2 to V7.4 is a low power application on the FRDM-KL25Z board. V7.4 comes with two major new features: Queue Sets and Tickles Idle Mode (see this article). The last one if of interest here.
FreeRTOS runs an IDLE task. This one runs when there is no other active task. That task calls an optional Idle task hook which is a perfect place to put the microcontroller into low power mode:
Task T1 Running
MCU on Eclipse 