Instruction Syntax and Addressing Modes

4.3.5Indirect Addressing

Indirect addressing uses one of 8 registers (R0...R7) to point memory addresses. The selected register can be post-modified. Modifications include increments, decrements, or increments by the value in the index register (R5). For post-modifications, the register increments or decrements itself by 2 for word operands and by 1 for byte operands. Syntaxes are shown in Table 4±9.

Table 4±9. Indirect Addressing Syntax

SyntaxOperation

name [dest,] [src,] ,*Rx++R5 [, next A] Premodify accumulator pointer if next A is included. Add Rx with R5. name *Rx++R5 [, src] [, next A]

name [dest,] [src,] ,*Rx [, next A]

Premodify accumulator pointer if next A is included. Use address

name *Rx [, src] [, next A]

pointed by Rx, Rx content unchanged

 

 

name [dest,] [src,] ,*Rx++ [, next A]

Premodify accumulator pointer if next A is included. Use address

name *Rx++ [, src] [, next A]

pointed by Rx, post increment Rx after use

 

 

name [dest,] [src,] ,*Rx±± [, next A]

Premodify accumulator pointer if next A is included. Use address

name *Rx±± [, src] [, next A]

pointed by Rx, post decrement Rx after use

 

 

Rx (x = 0 ± 7)

Address

Memory Operand

++ ±± ++R5

Note that the Rx registers treats data memory as a series of bytes. Therefore, when a word is loaded, Rx++ increments by 2 (Rx±± decrements by 2). When loading a word address into Rx, the address must be converted into a byte ad- dress (by multiplying by 2). For example, if we want Rx to point to the word ad- dress, 0x100, Rx should be loaded with 0x100*2=0x200.

Example 4.3.10 MOV A1~, *R1++R5, ++A

Refer to the initial processor state in Table 4±8 before execution of this instruction. Preincrement AP1. After preincrement A1 is AC22 and A1~ is AC6. The contents of the data memory location stored in R1 are loaded into accumulator AC6. R1 is then incremented by R5. Final result, AP1=22, AC6

=0xacb, R1 = R1 + R5 = 0x0202. Note that the addressing of the Rx registers is byte addressing.

Example 4.3.11 ADD A3~, A3, R6++R5, ±±A

Refer to the initial processor state in Table 4±8 before execution of this instruction. Predecrement AP3. After predecrement, A3 is AC28 and A3~ is AC12. The contents of the data memory location stored in R6 are added to AC28. The result is stored in accumulator AC12. R6 is then incremented by R5. Final result, AP3=28, AC12 = AC28 + *R6 = 0x11A2 + 0x12AC = 0x244E, R6 = R6+R5 = 0x3E6. Note that the Rx registers use byte addresses.

Assembly Language Instructions

4-15

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Texas Instruments MSP50C614 manual ±9. Indirect Addressing Syntax, SyntaxOperation
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MSP50C614 specifications

The Texas Instruments MSP50C614 is a microcontroller that belongs to the MSP430 family, renowned for its low power consumption and versatile functionality. Primarily designed for embedded applications, this microcontroller is favored in various industries, including consumer electronics, industrial automation, and healthcare devices.

One of the standout features of the MSP50C614 is its ultra-low power technology, which enables it to operate in various power modes. This makes it ideal for battery-powered applications, where energy efficiency is crucial. The MSP430 architecture allows for a flexible power management system, ensuring that energy is conserved while providing robust performance.

The MSP50C614 is equipped with a 16-bit RISC CPU that delivers high performance while maintaining low power usage. With a maximum clock frequency of 16 MHz, it can execute most instructions in a single cycle, resulting in swift operation and responsive performance. This microcontroller also comes with a generous flash memory capacity, allowing developers to store large amounts of code and data conveniently.

In terms of peripherals, the MSP50C614 is highly versatile. It features a range of digital and analog input/output options, including multiple timers, GPIO ports, and various communication interfaces like UART, SPI, and I2C. This extensive set of peripherals allows for seamless integration with other components and simplifies the design of complex systems.

The integrated 12-bit Analog-to-Digital Converter (ADC) stands out as a valuable characteristic of the MSP50C614. This feature enables the microcontroller to convert physical analog signals into digital data, making it particularly useful for sensing applications and real-time monitoring.

Another noteworthy technology employed in the MSP50C614 is its support for low-voltage operations. With a broad supply voltage range, this microcontroller can function efficiently in diverse environments and is suitable for low-power applications, enhancing its practicality.

Moreover, Texas Instruments provides software support in the form of Code Composer Studio and various libraries that make it easier for developers to program and utilize the MSP50C614 effectively.

In summary, the Texas Instruments MSP50C614 microcontroller is a powerful, low-power solution equipped with the features and technologies necessary for efficient operation in a wide array of applications. Its blend of performance, flexibility, and energy efficiency makes it a popular choice among engineers and designers looking to create innovative, sustainable designs in the rapidly evolving tech landscape.
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