In my earlier post I used a hacked together shield for building a clock based on Adafruit’s NeoPixel/WS2812 (“LED Clock with Kitchen Hot Pan Protector“). The new design supports now 8 parallel data streams, integrated realtime clock and wireless connectivity with the nRF24L01+ module.
NeoPixel Shield for FRDM Boards
Processor Expert components have an interesting concept: Events. Events are shown in green color with the ‘E’ (for Event):
TimerInt Component with Events
Newer microcontroller have increase RAM areas, making it suitable to run the application from RAM instead of FLASH. For the FRDM-K64F board and the Kinetis Design Studio (V1.1.1), I have explored how to run the application out of RAM instead of FLASH memory, both for P&E and Segger connections.
MK64FN1M0VLL12
Many applications need to store persistent (non-volatile) data at runtime: configuration data, error logs, sensor data, calibration values, etc. The question is: where to store that data? If it is only a few kBytes, an SD card or similar is an overkill. Adding an external EEPROM? Sure, that works, but adds an extra part to the design. Some microcontroller have internal EEPROM. But what if not? Why not using the microprocessor internal flash memory?
Internal FLASH vs. external EEPROM
I have been asked this question several times:
“How can I define my own interrupt vector with Processor Expert?”
So I think it deserves a short tutorial, if more than one person is asking this ;-).
My user interrupt in the vector table
In “IoT: FreeRTOS Down to the Micro Amps” I’m using an application with FreeRTOS to get down in micro amps low power mode. Well, nearly all or my applications are using FreeRTOS because it makes the application scalable and extensible. Still, for anyone not used to an RTOS, that might be a hard start. So here we go: how to get into the Kinetis Low Power LLS Mode *without* an RTOS.
Power Measurement
I have created and published on GitHub a new component ‘CriticalSection’:
Critical Section Component Methods
This component is a wrapper between my components and the problematic current implementation in Processor Expert (see EnterCritical() and ExitCritical(): Why Things are Failing Badly). It uses a flexible approach and uses macros to either use my modified version of EnterCritical() and ExitCritical(), or simply defaults to the original implementation.
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
I’m working with a student on building a small autonomous robot platform, based on the FRDM-KL25Z board. We integrated new software modules, compiled and linked, and then downloaded the application to the board. While debugging and stepping through the application startup, I had this:
The Debugger has lost communication on connection
Outsch! That’s not good. Even worse, trying to connect again to the board failed :-(. What happened?
You have decided: More than 52% voted in Part 1 that the next topic should be Timed Servo Moves. So here we go :-).
This is about how to move the servos over time, instead of moving it to the given position as fast as possible. I’m using a linear approach here: moving the servos linearly over time.
Moving Servo Motors
MCU on Eclipse 