Tag Archives: m0

A New Modular CMake Based Toolchain for Feather M0 HAL

In the past months, I developed firmware for a few Adafruit Feather M0 based projects. The reason why I use the Adafruit Feather platform, instead of using an MCU directly, is for modularity.

By using a board on sockets, it can be replaced at any later time with a more powerful one – or by one with additional peripherals.

The only downside of these boards is the programming toolchain. Either you use the Arduino IDE, or solder wires to the board to program the MCU directly using, e.g. Atmel Studio.

Using the Arduino IDE, I am bound to some really horrible written libraries. It is probably a good thing if you are really new to the concept of programming and just likes to get things working. In the long run, I think using these libraries will lead to bad coding habits. Yet, I like the simplicity of using this IDE – compiling and uploading the firmware using the bootloader.

The Atmel IDE is a pure Windows solution with a professional Visual Studio based IDE, introducing unnecessary complexity. The MCU is usually programmed directly, overwriting the bootloader.

So I worked on a compromise: A simple toolchain, which is reusing the tools from the Arduino IDE, also gives the comfort of the simple build and upload process, but it is based on CMake, a modular and widespread build system.

It is not meant to use for beginners. The idea is to provide a system which can be used in a prototype stage from professionals. Writing code to a fully abstract HAL which can later easily migrated to a professional firmware.

In this article, I will briefly describe this toolchain for the Feather M0 HAL. As for the HAL, it is a work in progress. It is meant as inspiration and example.

Update 2019-06-22: I concluded my tests on Linux successfully. For my tests, I used Ubuntu Linux with a compiled version of CMake. At this point, the available CMake package for this distribution was one version behind.

Requirements

I successfully tested the toolchain on macOS and it should work on Linux (Update: Successfully tested on Linux). There are a few requirements for both systems:

  • Works with any Adafruit Feather M0 based board.
  • Arduino IDE 1.8.9+
  • Python 3.7+
  • CMake 3.14+
Continue reading A New Modular CMake Based Toolchain for Feather M0 HAL

No Success with First Long Term Measurement

The first long term measurement I made, to test the behaviour of the sensor over a longer time range was a failure. After the five days with the device introduced in this post, the readings made absolute no sense.

plant-sensor-data

The sensor was not moved in the flower pot and the plant was once watered at the begin of the measurement. While it looked promising at the begin, the frequency suddenly went down again, which was very irritating. I am still investigating how this could happen.

To get closer to the real measurement of the final plant watering sensor, I started a new approach.

lucky-resistor-1

I soldered a header to one of the LED pads on a fully assembled plant sensor. Next I changed the device for the measurements.

lucky-resistor-2

Continue reading No Success with First Long Term Measurement

Plant Watering Sensor – Long Term Logging

To gather more long-term measurements for the capacitive method I use for my plant watering sensor, I created this small logging device. As you can see, it uses one of the plant watering sensor prototypes for the measurements. Instead of using the ATtiny13A on the board, it passes the oscillator signal directly to the microprocessor of the logging device.

In front there is a very small 128×32 OLED display, where I can see the current measured frequency in kHz. On top, the current time and date is visible, and on the right there is a graph where I can see the values from the last 48 hours graphically. There is not much visible in the graph, because I took the photo just after installing the sensor.

Every minute, the current average of measurements is stored in a CSV file on a SD card. After a few weeks I should be able to analyse this file and see the results. Here I am especially interested in the cycles from watering the plant until the soil got dry again. Continue reading Plant Watering Sensor – Long Term Logging