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USCI Overview

15.1 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

C mode

• SPI mode

15.2 USCI Introduction: UART Mode

In asynchronous mode, the USCI_Ax modules connect the MSP430 to an external system via two

external pins, UCAxRXD and UCAxTXD. UART mode is selected when the UCSYNC bit is cleared.

UART mode features include:

• 7- or 8-bit data with odd, even, or non-parity

• Independent transmit and receive shift registers

• Separate transmit and receive buffer registers

• LSB-first or MSB-first data transmit and receive

• Built-in idle-line and address-bit communication protocols for multiprocessor systems

• Receiver start-edge detection for auto-wake up from LPMx modes

• Programmable baud rate with modulation for fractional baud rate support

• Status flags for error detection and suppression

• Status flags for address detection

• Independent interrupt capability for receive and transmit

Figure 15-1 shows the USCI_Ax when configured for UART mode.

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SLAU144J–December 2004–Revised July 2013 Universal Serial Communication Interface, UART Mode

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