Texas Instruments MSP430x1xx manual I2CTCTL, I2C Transmit Control Register, I2CSSELx

I2C Module Registers

I2CTCTL, I2C Transmit Control Register

7 6 5 4

3 2 1 0

I2CWORD

I2CRM

I2CSSELx

I2CTRX

I2CSTB

I2CSTP

I2CSTT

rw−0 rw−0 rw−0 rw−0 rw−0 rw−0 rw−0 rw−0

Modifiable only when I2CEN = 0

I2CWORD	Bit 7	I2C word mode. Selects byte or word mode for the I2C data register.
		0	Byte mode
		1	Word mode
I2CRM	Bit 6	I2C repeat mode

0I2CNDAT defines the number of bytes transmitted.

1Number of bytes transmitted is controlled by software. I2CNDAT is unused.

I2CSSELx	Bits	I2C clock source select. When MST = 1 and arbitration is lost, the external SCL
	5−4	signal is automatically used.
		00	No clock − I 2C module is inactive
		01	ACLK
		10	SMCLK
		11	SMCLK
I2CTRX	Bit 3	I2C transmit. This bit selects the transmit or receive function for the I2C
		controller when MST = 1. When MST = 0, the R/W bit of the address byte
		defines the data direction. I2CTRX must be reset for proper slave mode
		operation.
		0	Receive mode. Data is received on the SDA pin.
		1	Transmit mode. Data transmitted on the SDA pin.
I2CSTB	Bit 2	Start byte. Setting the I2CSTB bit when MST = 1 initiates a start byte when
		I2CSTT = 1. After the start byte is initiated, I2CSTB is automatically cleared.
		0:	No action
		1:	Send START condition and start byte (01h), but no STOP condition.
I2CSTP	Bit 1	STOP bit. This bit is used to generate STOP condition. After the STOP
		condition, the I2CSTP is automatically cleared.
		0:	No action
		1:	Send STOP condition
I2CSTT	Bit 0	START bit. This bit is used to generate a START condition. After the start
		condition the I2CSTT is automatically cleared.
		0:	No action
		1:	Send START condition

15-22USART Peripheral Interface, I2C Mode