ChibiOS and STM32

ChibiOS is a compact and fast real-time operating system supporting multiple architectures. It offers a multi-threading scheduler and related APIs to manage threads scheduling and priorities, events and inter-thread communication. It also provide an Hardware Abstraction Layer.

STM32 is a broad family of 32-bit microcontrollers based on ARM Cortex-M architecture. With hundreds of different chips, STM32 covers a broad range of applications. Thanks to cheap and valuable development kits it is quite easy to evaluate them or create an prototype.

No matter what they say, you will not be able to appreciate the performance of these MCUs without a good scheduler. Here we will provide resources to getting started with STM32 development board using ChibiOS/RT as kernel and ChibiOS/HAL as drivers. Pick one and read it! If you like it don’t forget to Share the knowledge.

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PWM in hardware with STM32 Timer and ChibiOS

The Pulse Width Modulation (also known as PWM) is a digital modulation technique which uses duty-cycle of square waves to encode information. In communication field PWM surrendered to more advanced communication technique which uses more complex waveforms showing better noise rejection ratio and less transmission errors at highest data rate. Nevertheless, PWM is still used in infrared communication where data rate is very low but transmitter and receiver are cheap.

Anyway low rate communication is not the most relevant use case of PWM which is widely used in many fields continue reading...

Using STM32 ADC with ChibiOS ADC Driver

A microcontroller is a system which works on bits and bit streams more than analog signals, anyway those signals are still widely used in many fields especially in audio and power applications. An Analog to Digital Converter (or ADC) is a system that converts such kind of signals in a sequence of discrete values directly interpretable by the microcontroller. Such kind of converter is widely used in embedded systems to deal with those peripherals which works with analog signals like potentiometers, analog microphones or sensors.

Some examples?

Analog sensors which continue reading...

Using STM32 USART with ChibiOS Serial Driver

The serial communication in asynchronous mode is one of the simplest and most used methods to exchange data between a microcontroller and other devices. Such kind of communication can be achieved through a Universal Synchronous/Asynchronous Receiver Transmitter (or USART) as well as UART peripheral which actually is a subset of USART. Each STM32 microcontroller is equipped with multiple instances of these peripherals (from 2 up to 8) depending on the microcontroller model.

In this article, we are going to take an overview of serial communication protocols and peripherals continue reading...

Using STM32 GPIO with ChibiOS PAL Driver

The STM32 is equipped with an extremely flexible General Purpose Input Output (or GPIO) peripheral allowing to configure each Input/Output independently. The IO is the simplest interface between the STM32 and the outside world.

As we said in the article “From 0 to STM32“, there are many versions of the same peripherals across the various STM32’s sub-families and this is way each sub-family usually has its own Reference Manual. In this document it is possible to find all the functional information about GPIO and reading many RM we can notice that GPIO peripheral has three continue reading...

A close look to ChibiOS demos for STM32

A close look to ChibiOS demos for STM32

In this article we are going to take a deep look to ChibiOS default demos explaining how they works. We will also see how to create a new project and how to modify it in in order to create our own applications.

ChibiOS default demo are usually composed by some different folders and files. As example, in figure we can see the resources of the default demo for STM32 Nucleo F401RE. In general all the ChibiOS’ projects are characterised by a similar anatomy.

All demos have some folders, some configuration headers, a source file named main.c and a makefile. Additional notes continue reading...