Observer Design Pattern
The Observer Pattern According to the GoF book the Observer pattern “defines a one to many dependency between objects so that when one object changes state, all its dependents are...
Command Design Pattern
The Command Pattern The Gang of Four’s book gives the following definition of the command pattern: “The Command pattern encapsulates a request as an object, letting you parameterize clients with...
WiFi controlled Neo Pixels strips
In this project I explain how to drive NeoPixels with an Arduino M0 PRO (SAMD21) using the SPI peripheral with the DMA controller to create colored animated patterns. Since displaying...
STM32F4: using the DMA controller
When we want to transfer data to/from a peripheral device to perform I/O operations we generally use memory mapped IO: peripherals’ configuration and control registers are mapped to the microcontroller...
Interfacing a PS/2 keyboard to a microcontroller
In this article I explain how to interface a PS/2 keyboard to a microcontroller. Reading characters from a keyboard is just a matter of understanding the PS/2 protocol which is...
A simple game on STM32F429I Discovery board
In this past two weeks I spent some time learning how to create a simple graphic application for my STM32F429I-DISCOVERY board. Since it has a QVGA display with a ILI9341...
STM32: using the LTDC display controller
The STM32 LTDC has a peripheral called LTDC LCD TFT Display Controller which provides a digital parallel interface (DPI) for a variety of LCD and TFT panels. It sends RGB data in...
Arduino M0 PRO: programming the core ARM Cortex-M0+ and the SAMD21 MCU
A famous aphorism by computer scientist David Wheeler goes: “All problems in computer science can be solved by another level of indirection” (this is sometimes quoted as the fundamental theorem of...
Arduino M0 PRO: configuring the clock tree of SAMD21
The SAMD21 complex clock signal distribution system is designed to offer maximum flexibility and lets the programmer choose between performance and power consumption. The cperipherals that control the clock distribution...
Arduino M0 PRO: interrupt driven serial interface
SERCOM (SERial COMmunication interface) is the serial communication peripheral of the SAMD21. The SAMD21G18A has six peripheral instances (from SERCOM0 to SERCOM5) which can be configured to support USART, SPI...