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Texas Instruments MSP430x1xx manual 13-6USART Peripheral Interface, Uart Mode

Models: MSP430x1xx

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USART Operation: UART Mode

The URXWIE bit is used to control data reception in the idle-line multiprocessor format. When the URXWIE bit is set, all non-address characters are assembled but not transferred into the UxRXBUF, and interrupts are not generated. When an address character is received, the receiver is temporarily activated to transfer the character to UxRXBUF and sets the URXIFGx interrupt flag. Any applicable error flag is also set. The user can then validate the received address.

If an address is received, user software can validate the address and must reset URXWIE to continue receiving data. If URXWIE remains set, only address characters will be received. The URXWIE bit is not modified by the USART hardware automatically.

For address transmission in idle-line multiprocessor format, a precise idle period can be generated by the USART to generate address character identifiers on UTXDx. The wake-up temporary (WUT) flag is an internal flag double-buffered with the user-accessible TXWAKE bit. When the transmitter is loaded from UxTXBUF, WUT is also loaded from TXWAKE resetting the TXWAKE bit.

The following procedure sends out an idle frame to indicate an address character will follow:

1)Set TXWAKE, then write any character to UxTXBUF. UxTXBUF must be ready for new data (UTXIFGx = 1).

The TXWAKE value is shifted to WUT and the contents of UxTXBUF are shifted to the transmit shift register when the shift register is ready for new data. This sets WUT, which suppresses the start, data, and parity bits of a normal transmission, then transmits an idle period of exactly 11 bits. When two stop bits are used for the idle line, the second stop bit is counted as the first mark bit of the idle period. TXWAKE is reset automatically.

2)Write desired address character to UxTXBUF. UxTXBUF must be ready for new data (UTXIFGx = 1).

The new character representing the specified address is shifted out following the address-identifying idle period on UTXDx. Writing the first “don’t care” character to UxTXBUF is necessary in order to shift the TXWAKE bit to WUT and generate an idle-line condition. This data is discarded and does not appear on UTXDx.

13-6USART Peripheral Interface, UART Mode

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Page 266
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Texas Instruments MSP430x1xx manual 13-6USART Peripheral Interface, Uart Mode
Page 265 Page 267

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.