15.2.2 I2C Serial Data

I2C Module Operation

One clock pulse is generated by the master device for each data bit transferred. The I2C module operates with byte data. Data is transferred most significant bit first as shown in Figure 15−3.

The first byte after a START condition consists of a 7-bit slave address and the R/W bit. When R/W = 0, the master transmits data to a slave. When R/W = 1, the master receives data from a slave. The ACK bit is sent from the receiver after each byte on the 9th SCL clock.

Figure 15−3. I 2C Module Data Transfer

SDA
	MSB			Acknowledgement				Acknowledgement
			Signal From Receiver					Signal From Receiver
SCL
START	1	2	7	8	9	1	2	8	9		STOP
START				R/W	ACK				ACK		STOP
Condition (S)				R/W	ACK				ACK	Condition (P)
Condition (S)										Condition (P)

START and STOP conditions are generated by the master and are shown in Figure 15−3. A START condition is a high-to-low transition on the SDA line while SCL is high. A STOP condition is a low-to-high transition on the SDA line while SCL is high. The busy bit, I2CBB, is set after a START and cleared after a STOP.

Data on SDA must be stable during the high period of SCL as shown in Figure 15−4. The high and low state of SDA can only change when SCL is low, otherwise START or STOP conditions will be generated.

Figure 15−4. Bit Transfer on the I 2C Bus

Data Line

Stable Data

SDA

SCL

Change of Data Allowed

15-6USART Peripheral Interface, I2C 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 15.2.2 I2C Serial Data, 3. I 2C Module Data Transfer

Models: MSP430x1xx