General-Purpose Peripherals

Modern microcontrollers integrate several features that help in building stable and reliable embedded systems. Once the system is up and running, memory and peripherals can be accessed, and basic functionalities are in place. Only then can all the components of the system be initialized by activating the associated peripherals through the system registers, setting the correct frequencies for the clock lines, and configuring and activating interrupts. In this chapter, we will describe the interface exposed by the microcontroller to access built-in peripherals and some basic system functionalities. We will focus on the following topics:

• The interrupt controller
• System time
• Generic timers
• General-purpose input/output (GPIO)
• The watchdog

While these peripherals are often accessible through the hardware-support libraries implemented and distributed by chip manufacturers, our approach here involves fully understanding the hardware...