CPU Registers

3.2.5General−Purpose Registers R4 - R15

The twelve registers, R4−R15, are general-purpose registers. All of these registers can be used as data registers, address pointers, or index values and can be accessed with byte or word instructions as shown in Figure 3−7.

Figure 3−7. Register -Byte/Byte-Register Operations

Register-Byte Operation

High Byte

Low Byte

Unused

Byte-Register Operation

 

High Byte

Low Byte

 

 

 

 

Register

Byte

 

 

 

 

 

 

 

 

Memory

Byte

Memory

0h

Register

Example Register-Byte Operation

Example Byte-Register Operation

R5 = 0A28Fh

 

 

R5

= 01202h

 

R6 = 0203h

 

 

R6

= 0223h

 

Mem(0203h) = 012h

Mem(0223h) = 05Fh

ADD.B

R5,0(R6)

ADD.B

@R6,R5

 

 

08Fh

 

05Fh

 

 

 

+ 012h

 

+ 002h

 

 

 

 

 

 

 

 

 

 

0A1h

 

00061h

 

Mem (0203h) = 0A1h

R5

= 00061h

 

C = 0, Z = 0, N = 1

 

 

C = 0, Z = 0, N = 0

(Low byte of register)

(Addressed byte)

+ (Addressed byte)

+ (Low byte of register)

 

 

 

−>(Addressed byte)

−>(Low byte of register, zero to High byte)

3-8

RISC 16-Bit CPU

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Texas Instruments MSP430x1xx manual General−Purpose Registers R4 R15, 7. Register -Byte/Byte-Register Operations

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.