Datasheet

USCI Overview www.ti.com
17.1 USCI Overview
The universal serial communication interface (USCI) modules support multiple serial communication
modes. Different USCI modules support different modes. Each different USCI module is named with a
different letter. For example, USCI_A is different from USCI_B, etc. If more than one identical USCI
module is implemented on one device, those modules are named with incrementing numbers. For
example, if one device has two USCI_A modules, they are named USCI_A0 and USCI_A1. See the
device-specific data sheet to determine which USCI modules, if any, are implemented on which devices.
The USCI_Ax modules support:
• UART mode
• Pulse shaping for IrDA communications
• Automatic baud rate detection for LIN communications
• SPI mode
The USCI_Bx modules support:
• I
2
C mode
• SPI mode
17.2 USCI Introduction: I
2
C Mode
In I
2
C mode, the USCI module provides an interface between the MSP430 and I
2
C-compatible devices
connected by way of the two-wire I
2
C serial bus. External components attached to the I
2
C bus serially
transmit and/or receive serial data to/from the USCI module through the 2-wire I
2
C interface.
The I
2
C mode features include:
• Compliance to the Philips Semiconductor I
2
C specification v2.1
– 7-bit and 10-bit device addressing modes
– General call
– START/RESTART/STOP
– Multi-master transmitter/receiver mode
– Slave receiver/transmitter mode
– Standard mode up to 100 kbps and fast mode up to 400 kbps support
• Programmable UCxCLK frequency in master mode
• Designed for low power
• Slave receiver START detection for auto-wake up from LPMx modes
• Slave operation in LPM4
Figure 17-1 shows the USCI when configured in I
2
C mode.
450
SLAU144J–December 2004–Revised July 2013
Universal Serial Communication Interface, I
2
C Mode
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