I2C Module Operation

Automatic Data Byte Counting

Automatic data byte counting is supported in master mode with the I2CNDAT register. When I2CRM = 0, the number of bytes to be received or transmitted is written to I2CNDAT. A STOP condition is automatically generated after I2CNDAT number of bytes have been transferred.

Note: I2CNDAT Register

Do not change the I2CNDAT register while I2CBB = 1 and I2CRM = 0.

Otherwise, unpredictable operation may occur.

Slave Mode

In slave mode, transmit and receive operations are controlled automatically by the I2C module. The slave transmitter and slave receiver modes are shown in Figure 15−11 and Figure 15−12.

In slave receiver mode, serial data bits received on SDA are shifted in with the clock pulses that are generated by the master device. The slave device does not generate the clock, but it can hold SCL low if intervention of the CPU is required after a byte has been received. In slave receiver mode, every byte received will be acknowledged. There is no way for a slave to generate a NACK condition for received data.

Slave transmitter mode is entered when the slave address byte transmitted by the master is the same as its own address and a set R/W bit has been transmitted indicating a request to send data to the master. The slave transmitter shifts the serial data out on SDA with the clock pulses that are generated by the master device. The slave device does not generate the clock, but it will hold SCL low while intervention of the CPU is required after a byte has been transmitted.

Note: I2CTRX Bit In Slave Mode

The I2CTRX bit must be cleared for proper slave mode operation.

15-12USART Peripheral Interface, I2C Mode

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Texas Instruments MSP430x1xx manual Automatic Data Byte Counting
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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.
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