Return From Interrupt

System Reset and Initialization

The interrupt handling routine terminates with the instruction:

RETI (return from an interrupt service routine)

The return from the interrupt takes 5 cycles to execute the following actions and is illustrated in Figure 2−8.

1)The SR with all previous settings pops from the stack. All previous settings of GIE, CPUOFF, etc. are now in effect, regardless of the settings used during the interrupt service routine.

2)The PC pops from the stack and begins execution at the point where it was interrupted.

Figure 2−8. Return From Interrupt

	Before			After
		Return From Interrupt


	Item1			Item1
			SP
	Item2			Item2
	Item2			Item2

	PC			PC
SP			TOS
	SR			SR
	SR			SR

TOS

Interrupt Nesting

Interrupt nesting is enabled if the GIE bit is set inside an interrupt service routine. When interrupt nesting is enabled, any interrupt occurring during an interrupt service routine will interrupt the routine, regardless of the interrupt priorities.

2-12System Resets, Interrupts, and Operating Modes

MSP430x1xx specifications

The Texas Instruments MSP430x1xx series is a family of ultra-low-power microcontrollers that are highly regarded in the embedded systems community for their versatility and performance. Designed for applications ranging from portable instrumentation to low-power industrial devices, the MSP430x1xx combines flexibility and efficiency with advanced features tailored for energy-sensitive applications.

One of the standout characteristics of the MSP430x1xx is its ultra-low-power operation. This series offers several low-power modes that can significantly extend battery life in portable devices. The microcontroller can be in active mode, low-power mode, or even in a deep sleep state, allowing developers to optimize power consumption based on the application's requirements. In fact, some configurations can operate at just a few microamps, making it ideal for battery-operated devices.

Another key feature is the 16-bit RISC architecture that provides powerful processing capabilities while maintaining a low power profile. The MSP430x1xx series supports a maximum clock speed of 16 MHz, allowing for efficient task execution while consuming minimal energy. This architecture ensures that programs run smoothly while the microcontroller remains energy efficient.

The MSP430x1xx is equipped with various integrated peripherals, including analog-to-digital converters (ADCs), timers, and communication interfaces like UART, SPI, and I2C. The inclusion of a powerful ADC enables the microcontroller to handle sensor readings with high accuracy, making it suitable for applications like environmental monitoring and medical devices. The integrated timers provide essential functionality for real-time applications, allowing for event-driven programming and precise timing control.

Memory options in the MSP430x1xx series are also robust, with configurations offering flash memory sizes from 1 KB to 64 KB. This flexibility allows developers to choose the optimal memory size for their specific applications, accommodating a wide range of requirements.

Additionally, the MSP430x1xx microcontrollers are designed with a wide operating voltage range, typically from 1.8V to 3.6V, making them compatible with various power sources and further enhancing their usability in diverse applications.

In summary, the Texas Instruments MSP430x1xx series of microcontrollers is an excellent choice for developers seeking low-power, high-performance solutions for embedded applications. With an efficient architecture, a rich set of peripherals, and flexible memory options, these microcontrollers are positioned to meet the growing demands of modern electronic designs, particularly in battery-powered and energy-sensitive applications.

Texas Instruments MSP430x1xx manual Return From Interrupt, Interrupt Nesting

Models: MSP430x1xx