Introduction to Microcontroller Interrupts

Interrupts play a crucial role in the realm of embedded systems and microcontroller projects. They allow for responsive and efficient handling of external events, whether they're hardware signals or other critical tasks. This guide delves into the specifics of enabling and disabling interrupts on different microcontroller platforms, focusing on common challenges and providing a flexible approach for developers.

Understanding Interrupts in Microcontrollers

Interrupts are signals that a peripheral generates to request the processor's attention. In embedded systems, handling these interrupts is essential for creating efficient and responsive applications. The common task of managing interrupts is facilitated by the attachInterrupt and detachInterrupt functions in the Arduino IDE, which are widely used to enable and disable interrupts on ARM-based microcontrollers like the ESP32.

Enabling and Disabling Interrupts on Arduino IDE

The Arduino IDE provides a straightforward way to manage interrupts through its attachInterrupt and detachInterrupt functions. These functions work seamlessly on AVR-based controllers like the ATmega series and ESP32, but issues can arise with other controllers, such as the ATtiny85. The ATtiny85, despite being an AVR chip, is not natively supported by the Arduino IDE for interrupt management due to its limited features. This discrepancy highlights the importance of having a deeper understanding of the underlying hardware and assembly language.

The ATtiny85 and Interrupt Management

Developers working with the ATtiny85 often find themselves puzzled when they encounter the same functions in the Arduino IDE are not functional. Instead, they need to resort to assembly language to manage interrupts effectively. The key lies in understanding the interrupt vectors and the register manipulation necessary for interrupt handling. For example, the ATtiny85 uses the MCUCR, MCUCSR, and SPCR registers to control and manage interrupts. Familiarity with these registers is imperative for effective interrupt handling on this particular microcontroller.

Manual Assembly Code for Interrupt Handling

For the ATtiny85, manually writing assembly code is necessary to enable or disable interrupts. Here is an example of how this can be done:

tasm volatile("cli
" /* Disable interrupts */);
tpbrc 5D, PORTB, 03, DDRB, PORTB, 0C, MCUCR, 09, GICR, 0B, SREG, 0A, sei
" /* Enable interrupts */);