System Reset and Initialization

2.1 System Reset and Initialization

The system reset circuitry shown in Figure 2−1 sources both a power-on reset (POR) and a power-up clear (PUC) signal. Different events trigger these reset signals and different initial conditions exist depending on which signal was generated.

Figure 2−1. Power-On Reset and Power-Up Clear Schematic

VCC

VCC

 

 

 

 

 

 

 

 

 

 

Brownout

 

 

POR

 

Reset

 

 

Detect#

 

 

 

VCC

 

 

POR

S

 

Delay#

POR

S

 

Latch

 

 

POR

 

0 V

 

0 V ~ 50us

 

 

 

 

 

 

 

 

 

 

 

SVS_POR§

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RST/NMI

 

 

 

 

 

 

 

0 V

R

Delay

WDTNMI

WDTSSEL

WDTQn

WDTIFG

EQU

KEYV

(from flash module)

 

S

 

 

S

 

Resetwd1

S

PUC

S

 

Latch

 

S

 

Resetwd2

R

 

PUC

MCLK

From watchdog timer peripheral module

‡ Devices with BOR only

# Devices without BOR only § Devices with SVS only

A POR is a device reset. A POR is only generated by the following three events:

-Powering up the device

-A low signal on the RST/NMI pin when configured in the reset mode

-An SVS low condition when PORON = 1.

A PUC is always generated when a POR is generated, but a POR is not generated by a PUC. The following events trigger a PUC:

-A POR signal

-Watchdog timer expiration when in watchdog mode only

-Watchdog timer security key violation

-A Flash memory security key violation

2-2

System Resets, Interrupts, and Operating Modes

Page 20
Image 20
Texas Instruments MSP430x1xx manual System Reset and Initialization, 1. Power-On Reset and Power-Up Clear Schematic

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.