There are different ways to ruin a Linux system. For the Raspberry Pi which uses a micro SD card as the storage device by default, it comes with two challenges:
- Excessive writes to the SD card can wear it out
- Sudden power failure during a SD card write can corrupt the file system
For problem one I do I have a mitigation strategy (see “Log2Ram: Extending SD Card Lifetime for Raspberry Pi LoRaWAN Gateway“). Problem two can occur by user error (“you shall not turn it off without a sudo poweroff!”) or with the event of a power outage or black out. So for that problem I wanted to build a UPS for the Raspberry Pi.
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.
Doing Mini Sumo robot competition is really fun, and there is yet another one coming to end the current university semester. For several years we have used our own sumo robot, and this is the one used in the course this year too. But for future and extended events we are exploring a new robot. I proudly present the concept of the next generation sumo robot for the year 2018:
The NXP Freedom boards are very popular. Many of them are inexpensive (less than $20), include a debug interface and can be easily extended with extra shields or boards. Especially the FRDM-KL25Z is very popular: I’m getting told because of Processor Expert and tutorials available on web sites like this one ;-).
Unfortunately there are no small or breadboard friendly Kinetis boards available. There is the NXP LPC800-DIP but with no onboard debugger and without Processor Expert support. We have the tinyK20, but projects tend to use more CPU power, FLASH and RAM space than what the tinyK20 board (50 MHz, 128 KByte FLASH, 16 KByte RAM) can provide. So we ended up designing the big brother of the first tinyK20: the tinyK22 with 120 MHz, 512 KByte of FLASH and 128 KByte of RAM.