3 XT2 Oscillator, Disabling the DCO | Texas Instruments MSP430x1xx

Basic Clock Module Operation

4.2.3XT2 Oscillator

Some devices have a second crystal oscillator, XT2. XT2 sources XT2CLK and its characteristics are identical to LFXT1 in HF mode. The XT2OFF bit disables the XT2 oscillator if XT2CLK is not used for MCLK or SMCLK as shown in Figure 4−3.

XT2 may be used with external clock signals on the XT2IN pin. When used with an external signal, the external frequency must meet the datasheet parameters for XT2.

Figure 4−3. Off Signals for Oscillator XT2

XT2OFF
CPUOFF
SELM1	XT2Off (Internal signal)
SELM0
SCG1
SELS

4.2.4Digitally-Controlled Oscillator (DCO)

The DCO is an integrated ring oscillator with RC-type characteristics. As with any RC-type oscillator, frequency varies with temperature, voltage, and from device to device. The DCO frequency can be adjusted by software using the DCOx, MODx, and RSELx bits. The digital control of the oscillator allows frequency stabilization despite its RC-type characteristics.

Disabling the DCO

Software can disable DCOCLK by setting SCG0 when it is not used to source SMCLK or MCLK in active mode, as shown in Figure 4−4.

Figure 4−4. On/Off Control of DCO

CPUOFF

XSELM1

SCG1

SELS

SMCLK

SCG0

DQ CL

POR

DCOCLK

DCOCLK_on

1:on

0:off

DCO_Gen_on

1:on

0:off

4-6	Basic Clock Module

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 3 XT2 Oscillator, Digitally-Controlled Oscillator DCO

Models: MSP430x1xx