Usart Operation SPI Mode, Simo | Texas Instruments MSP430x1xx

USART Operation: SPI Mode

14.2 USART Operation: SPI Mode

In SPI mode, serial data is transmitted and received by multiple devices using a shared clock provided by the master. An additional pin, STE, is provided as to enable a device to receive and transmit data and is controlled by the master.

Three or four signals are used for SPI data exchange:

- SIMO	Slave in, master out
	Master mode: SIMO is the data output line.
	Slave mode: SIMO is the data input line.
- SOMI	Slave out, master in
	Master mode: SOMI is the data input line.
	Slave mode: SOMI is the data output line.
- UCLK	USART SPI clock
	Master mode: UCLK is an output.
	Slave mode: UCLK is an input.
- STE	Slave transmit enable. Used in 4-pin mode to allow multiple
	masters on a single bus. Not used in 3-pin mode.
	4-Pin master mode:
	When STE is high, SIMO and UCLK operate normally.
	When STE is low, SIMO and UCLK are set to the input direction.
	4-pin slave mode:
	When STE is high, RX/TX operation of the slave is disabled and
	SOMI is forced to the input direction.
	When STE is low, RX/TX operation of the slave is enabled and
	SOMI operates normally.

14.2.1 USART Initialization and Reset

The USART is reset by a PUC or by the SWRST bit. After a PUC, the SWRST bit is automatically set, keeping the USART in a reset condition. When set, the SWRST bit resets the URXIEx, UTXIEx, URXIFGx, OE, and FE bits and sets the UTXIFGx flag. The USPIEx bit is not altered by SWRST. Clearing SWRST releases the USART for operation. See also chapter USART Module, I2C mode for USART0 when reconfiguring from I2C mode to SPI mode.

Note: Initializing or Re-Configuring the USART Module

The required USART initialization/re-configuration process is:

1)Set SWRST (BIS.B #SWRST,&UxCTL)

2)Initialize all USART registers with SWRST=1 (including UxCTL)

3)Enable USART module via the MEx SFRs (USPIEx)

4) Clear SWRST via software (BIC.B #SWRST,&UxCTL)

5)Enable interrupts (optional) via the IEx SFRs (URXIEx and/or UTXIEx) Failure to follow this process may result in unpredictable USART behavior.

14-4USART Peripheral Interface, SPI Mode

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 Usart Operation SPI Mode, Simo

Models: MSP430x1xx

14.2 USART Operation: SPI Mode

- SIMO

- SOMI

- UCLK

14.2.1 USART Initialization and Reset

MSP430x1xx specifications