Category Archives: Embedded Components

Everything about Processor Expert Embedded Components

Tutorial: Ultra Low Cost 2.4 GHz Wireless Transceiver with the FRDM Board

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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

nRF24L01+ Module Detail

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Hacking the Heating System for Cooling – Geothermal Drilling with extra Benefits

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Summer finally has arrived in Switzerland. Yes, I live in a moderate climate zone, but if the outside temperature goes above 28-30° Celsius as these days, then sleeping at night is not that comfortable as it should be in my view. Luckily, I’m in a good constructed house with good insulation, so it takes a few days until it heats up. But I love to keep the temperature below 25° Celsius, especially at night. I do have a heating system which combines geothermal and solar heating. The question is: how can I use it for cooling during hot summer days? The solution: some extra plumbing, a Freescale Tower system and the Freescale FRDM-KL25Z board 🙂

FRDM-KL25Z with Arduino Data Logger Shield

FRDM-KL25Z with Arduino Data Logger Shield controlling Heating/Cooling System

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FRDM-KL25Z talks to Android Phone

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Ok, I still do not own an Android phone, but I know many readers of this blog do, and there were several questions how to use the FRDM-KL25Z with Android. And here is something exciting I just saw today: Kai Liu posted information how to connect the FRDM-KL25Z with USB OTG (On-The-Go) to Android: FRDM-KL25Z now talks to Android Phone

He published the S19 file so you can try things out. He still needs to organize the sources and decide on how to publish it (I hope it will be available soon).

If you do not own a FRDM-KL25Z RevE, then you need to consider this post about a hardware change: USB host HID demo times out on FRDM-KL25Z with reproduced USB host

Happy Droiding 🙂

USB MSD Host for the FRDM-K20D50M Board

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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

FRDM-K20D50M as USB MSD Host

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FreeRTOS Heap with Segmented Kinetis K SRAM

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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

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 →

Yet another Bluetooth Firmware: BC04

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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 :-).

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Low Power with FreeRTOS: Tickless Idle Mode

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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

Task T1 Running

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Using the FRDM-KL25Z as USB Keyboard

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I miss my old DELL laptop. Ok, the new one I received from IT services is not bad. It is faster and has a better screen. But I’m not really happy with the new keyboard. With the previous keyboard I was able to do a ‘PrtnScrn’ with a single key press. With the new one I need to press Fn + PrntScrn. And this is impossible to do with one hand:

Impossible to reach Prnt Scrn

Impossible to reach Fn+Prnt Scrn with one hand!

Yes, I have two hands ;-). But many times I need to do ‘print screen’ while having my other hand on the mouse :-(.What else can I do?

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Using Keil µVision 4 (ARM-MDK) with Processor Expert Driver Suite

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❗ This article has been written for the version 4 of µVision. There is an update for version 5 of µVision here: “Using Keil μVision 5 with Processor Expert“

The good thing with using ARM microcontroller is: there are plenty of tool choices. Even myself, I’m using multiple different tool chains. And while I’m heavily using Eclipse, there are non-Eclipse tool chains which have their advantages too.

The cool thing with CodeWarrior is that beside of Eclipse based, it comes with Processor Expert integrated. And I’m using Processor Expert a lot in my projects. But using Processor Expert does not mean I’m limited to CodeWarrior or Eclipse. So I can use CodeRed or IAR as tool chain with it. And this post is about using Processor Expert with the µVision tool chain from Keil/ARM.

Keil uVision Splash Screen

Keil uVision Splash Screen

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Using the HC-06 Bluetooth Module

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After my first post using a Bluetooth module, things have evolved a bit. The challenge with these Bluetooth modules is: they look the same, but having different firmware. I did not fully realize that until I have ordered another bluetooth module from dx.com:

DX.com Bluetooth Module (HC-06)

DX.com Bluetooth Module (HC-06)

That module comes already on a carrier, so I assumed I can use the same driver as for my other module. I was wrong :-(.

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