tinyK22 Board Rev 1.3 released

The tinyK22 board is a tiny micro controller board we use at the Lucerne University of Applied Sciences and Arts. It is used in many research project, used in lectures and labs and used in most student projects. Because there was no small and breadboard friendly NXP Kinetis board with a debug interface available, we developed one featuring the NXP K22FN512, named the ‘tinyK22‘. Because of the success and high demand we stated a new large production run and used this to upgrade the board to the new Rev 1.3: you might notice already the color change :-).

tinyK22

tinyK22

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How to get Data off an Embedded System: FatFS with USB MSD Host and FreeRTOS Direct Task Notification

This is a follow-up article of my earlier project presented in “FatFS, MinIni, Shell and FreeRTOS for the NXP K22FN512“. I wanted to extend it with a USB MSD (memory stick) device: The USB storage device gets automatically mounted, and depending on a configuration (.ini) file on the memory device I can perform various actions, for example automatically copy data from the SD card to the USB device. For example the system logs data, and to get the data I insert the memory stick, it copies the data on it and automatically unmounts it, and I can remove the memory stick.

FRDM-K22F USB Host Mode with Memory Sticks

FRDM-K22F USB Host Mode with Memory Sticks

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Disabling NMI (Non Maskable Interrupt) Pin

The NMI is a special interrupt on ARM Cortex-M architecture: as the name indicates, it cannot be ‘masked’ by the usual ‘disable interrupts’ flags (PRIMASK, BASEPRI), similar to the Reset signal.

cortex-m-vector-table

cortex-m-vector-table (Source: adapted from arm.com)

Dealing with the reset signal is kind of obvious, and most designs and boards have it routed to a reset button or similar. The NMI is less obvious if you don’t pay attention to it: most ARM-Cortex implementations and boards have the NMI signal routed to a pin and are ‘hiding’ it in the schematics behind a normal GPIO pin or port: if you don’t pay attention to the NMI functionality, the board might not work as intended.

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FatFS, MinIni, Shell and FreeRTOS for the NXP K22FN512

I’m using the NXP Kinetis K22FN512 in many projects, either with the FRDM-K22F or on the tinyK22: with 120 MHz, 512 KByte FLASH and 128 KByte it has plenty of horsepower for many projects. The other positive thing is that it is supported by the NXP MCUXpresso IDE and SDK. I have now created an example which can be used as base for your own project, featuring FreeRTOS, FatFS, MinIni and a command line shell.

FRDM-K22F with SD Card

FRDM-K22F with SD Card

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Tutorial: Maximum Clock Frequency for Kinetis using MCUXpresso Clock Tools

The tinyK22 board with the NXP K22FN512 is a bread-board-friendly small board with a 8 MHz external oscillator:

tinyK22 Board

tinyK22 Board

This tutorial is about how to use the NXP MCUXpresso Clock configuration and configure the board to the maximum clock frequency of 120 MHz. The same steps apply to many other boards, including the FRDM-K22F one.

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Tutorial: CRC32 Checksum with the KBOOT Bootloader

In “Flash-Resident USB-HID Bootloader with the NXP Kinetis K22 Microcontroller” I presented how I’m using the tinyK22 (or FRDM-K22F) with a flash resident USB HID bootloader. To make sure that the loaded application is not corrupted somehow, it is important to verify it with a Cyclic redundancy Checksum (CRC). The NXP KBOOT Bootloader can verify such a CRC, but how to generate one and how to use it is not really obvious (at least to me), so this article explains how to generate that CRC.

CRC Values for KBOOT

CRC Values for KBOOT

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Flash-Resident USB-HID Bootloader with the NXP Kinetis K22 Microcontroller

The tinyK22 board (see “tinyK22 Boards arrived“) gets rolled out at the Lucerne University of Applied Sciences and Arts, so I thought I write-up an article this weekend how to use that board with a Flash Resident Bootloader.

tinyK22 with USB HID Bootloader

tinyK22 with USB HID Bootloader

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Adding a Delay to the ARM DAPLink Bootloader

The ARM mbed USB MSD bootloader which is used on many silicon vendor boards has a big problem: it is vulnerable to operating systems like Windows 10 which can brick your board (see “Bricking and Recovering OpenSDA Boards in Windows 8 and 10“). To recover the board, typically a JTAG/SWD programmer has to be used. I have described in articles (see links section) how to recover from that situation, including using an inofficial new bootloader which (mostly) solves the problem. The good news is that ARM (mbed) has released an official and fixed bootloader. The bad news is that this bootloader does not work on every board because of a timing issue: the bootloader mostly enters bootloader mode instated executing the application.

DAPLink in Bootloader Mode

DAPLink in Bootloader Mode

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Recovering and Updating the NXP OpenSDA Bootloader with P&E Multilink and MCUXpresso IDE

Many of the NXP OpenSDA boot loaders are vulnerable to Windows 8.x or Windows 10: write accesses of Windows can confuse the factory bootloader and make the debug firmware and bootloader useless. In this post I show how to recover the bootloader using MCUXpresso IDE and the P&E Universal Multilink.

Using P&E Multilink Universal to restore the OpenSDA Bootloader on NXP FRDM-K22F Board

Using P&E Multilink Universal to restore the OpenSDA Bootloader on NXP FRDM-K22F Board

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Bricking and Recovering OpenSDA Boards in Windows 8 and 10

Getting a board from a distributor like Farnell/Element14/Mouser (add your own distributor) means that chances are high that the default firmware on it is written years from now because the inventory has not been updated, or because boards are still produced with that original firmware (because of testing?). So what happens if I use board with a firmware developed pre-Windows 8/10 area?

Freshly Unboxed NXP FRDM-KL25Z Board

Freshly Unboxed NXP FRDM-KL25Z Board

It might work, but chances are high that the bootloader and firmware is not ready for the ‘modern age’, and as a result the board might be bricked. If you still have a Windows 7 machine around (I do!), you are lucky. If not, then you need to read this article….

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