I2C Module Operation

15.2.3 I2C Addressing Modes

The I2C module supports 7-bit and 10-bit addressing modes.

7-Bit Addressing

In the 7-bit addressing format, shown in Figure 15−5, the first byte is the 7-bit slave address and the R/W bit. The ACK bit is sent from the receiver after each byte.

Figure 15−5. I 2C Module 7-Bit Addressing Format

1

S

7

1

1

8

1

8

1

1

Slave Address

R/W

ACK

Data

ACK

Data

ACK

P

10-Bit Addressing

In the 10-bit addressing format, shown in Figure 15−6, the first byte is made up of 11110b plus the two MSBs of the 10-bit slave address and the R/W bit. The ACK bit is sent from the receiver after each byte. The next byte is the remaining 8 bits of the 10-bit slave address, followed by the ACK bit and the 8-bit data.

Figure 15−6. I 2C Module 10-Bit Addressing Format

1

7

1

1

8

1

8

1

1

 

 

 

 

 

 

 

S

Slave Address 1st byte R/W ACK Slave Address 2nd byte

ACK

Data

ACK P

1 1 1 1 0 X X

Repeated START Conditions

The direction of data flow on SDA can be changed by the master, without first stopping a transfer, by issuing a repeated START condition. This is called a RESTART. After a RESTART is issued, the slave address is again sent out with the new data direction specified by the R/W bit. The RESTART condition is shown in Figure 15−7.

Figure 15−7. I 2C Module Addressing Format with Repeated START Condition

1

7

1

1

8

1

1

7

1

1

8

1

1

S

Slave Address

R/W

ACK

Data

ACK

S

Slave Address

R/W

ACK

Data

ACK

P

 

1

 

 

Any

 

 

1

 

 

Any Number

 

 

Number

USART Peripheral Interface, I2C Mode

15-7

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Texas Instruments MSP430x1xx manual 15.2.3 I2C Addressing Modes, Bit Addressing, Repeated Start Conditions
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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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