One of the most important aspects of the ‘IoT’ world is having a secure communication. Running MQTT on lwip (see “MQTT with lwip and NXP FRDM-K64F Board“) is no exception. Despite of the popularity of MQTT and lwip, I have not been able to find an example using a secure TLS connection over raw/native lwip TCP :-(. Could it be that such an example exists, and I have not found it? Or that someone implemented it, but has not published it? Only what I have found on the internet are many others asking for the same kind of thing “running MQTT on lwip with TLS”, but there was no answer? So I have to answer my question, which seems to be a good thing anyway: I can learn new things the hard way :-).
Block diagram MQTT Application with TLS using lwip
There are many mergers going on in the industry, and one of the largest one was in 2016 the integration of Freescale Semiconductor with NXP Semiconductors, with both providing Eclipse based IDE’s to their customer base. Consequently, the company merger triggered a merger of the IDE’s, and last week NXP has released the result: the MCUXpresso IDE.
One of the biggest road blocks (beside of closed source) using the BLE (Bluetooth Low Energy) stack from NXP is that it requires expensive tools to compile and build the stack. The good news is that I have now the NXP BLE stack for the Mikroelektronika Hexiwear ported to Eclipse and GNU gcc build tools for ARM 🙂
But one issue I have faced several times is that the board works fine while debugging and connected and powered by a host machine, but does not startup sometimes if powered by a battery or started without a debugger attached. I have found that the EzPort on the microcontroller is causing startup issues.
Playing with RFID and NFC is definitely fun :-), and they are everywhere! For a research project I’m exploring different RFID tags and solutions. I several types around for a long time, but never found the time to actually work on it, so last nightI thought I give it a try, and I have it working with GNU ARM and Eclipse, powered by the NXP FRDM-K64F board 🙂
I kind of hoped that after “Why I don’t like printf()” and all my other articles about printf and semihosting, that topic would be 200% handled and I won’t have to deal with any more. Well, I was wrong and underestimated how the Kinetis SDK is interfering with semihosting. And I underestimated how many of my readers are still using semihosting (even as there are other and better alternatives), so I keep getting questions and requests for help. That’s ok, and I hope I can help :-).
So here is yet again another post about how to turn on semihosting with Eclipse, GNU ARM Embedded and the Kinetis SDK v2.0. This time with the FRDM-K64F board:
For a university research project I need a fast microcontroller with lots of RAM and FLASH memory. I have ordered a TWR-KV58F220M board from NXP which arrived yesterday. The special thing is that it has on of these new ARM Cortex-M7F on it:
My wife tells me that I have too many boards on my desk. That is only *partially* correct: there are many, but not *too* many. But I’m working on too many tasks, but that’s a different aspect :-). I’m using more and more the Kinetis SDK V2.0, and as a result of this I have multiple SDKs installed on my machine. Because with the SDK V2.0 I get a download for each device/board installed (see “First NXP Kinetis SDK Release: SDK V2.0 with Online On-Demand Package Builder“). So my list of SDK folders is growing, as shown with the ‘New SDK 2.x’ wizard in Kinetis Design Studio:
Multiple Kinetis SDKs
The same time, the amount of free disk space is reducing. What if I could combine all these SDK’s?
I don’t know if it is the same for you. But for me, configuring the pins on these new ARM microcontroller is a challenge: Most pins can do multiple functions, such as be used as I²C, UART or GPIO pins.
Configuring the pins ‘by hand’ is difficult, error-prone and usually the first thing I need to do for a new project/device. NXP developed a new tool for this task and previewed it at FTF 2016. It is available now both as web (online) and desktop (locally installed) tool. At FTF it was possible to play with an engineering release: time to get my hands on the public release :-). And as more and more student projects will start using that tool for their boards, I better have a tutorial for it :-).
I’m using FreeRTOS in most of my applications. There were only a few exceptions where an RTOS has to be used in safety critical systems: there usually it is not permitted to use any dynamic memory allocation because this adds the risk that a memory allocation could fail at runtime because of memory fragmentation or memory leak. And FreeRTOS uses a dynamic memory (heap) for the task stacks and the RTOS resources including semaphore, mutex and queues.
This is now a thing of the past. This week a new FreeRTOS Version 9 was released which does not need any dynamic memory allocation anymore: it is possible now to build completely statically allocated systems with FreeRTOS :-).
Dynamic and Static Memory Allocation in FreeRTOS V9.0.0
The challenge with the selection of a microcontroller for a project is: which one has the required number of UART, I2C, SPI? Combine this with the desired package (48pins, 64pins? LQFN?), the needed FLASH and RAM size and then even the hundreds of available microcontroller shrink to a handful only. And many times I need to make compromises: such as I need two hardware I2C, but the microcontroller matching all my other needs has only one I2C hardware. So I might end up with bit-banging the slower I2C bus. Doable, but not ideal.
What is cool that some of the newer NXP Kinetis microcontroller come with an interesting hardware: FlexIO. A peripheral hardware which allows me to implement a custom protocol, including driving WS2812B (Adafruit NeoPixel) LEDs with a FRDM-KL43Z board:
I mentioned the hands-on sessions on FreeRTOS I do this week at NXP FTF Tech Forum in Austin in my previous post. What we are using in the session is an Eclipse plugin in Kinetis Design Studio showing all kinds of FreeRTOS information: