Generation of Arduino Interrupts

The projects aims to setup a hardware timer that will generate an interrupt as a background function to run at regular intervals when working on microcontroller projects.

Interrupts are signal that interrupt the normal flow of a program. They are usually used for hardware devices that require immediate attention when events occur. To handle the periodic interrupt, the interrupt triggers an Interrupt Service Routine (ISR). The device sets up the 8-bit Timer2 to generate interrupts on an Arduino ATmega168. This microcontroller has several I/O systems such as Digital I/O, PWM, A/D Inputs, and Serial port while having 3 internal hardware timers. The Arduino library does not directly cover using a timer to generate periodic interrupts although it makes use of some of the timer features.

The microcontroller stops running the main code when a new character arrives the UART system which generates an interrupt, and jumps to an ISR for the specific interrupt. The new character is grabbed by this ISR from the UART, places it into a buffer, and then clears the interrupt and returns. The microcontroller goes back to the main code when the ISR returns, and continues where it left off.

Rest of the project