Datasheet

550
32072H–AVR32–10/2012
AT32UC3A3
25.6 Functional Description
25.6.1 USART Operating Modes
The USART can operate in several modes:
•Normal
• RS485, described in Section 25.6.5 ”RS485 Mode” on page 560
• Hardware handshaking, described in Section 25.6.6 ”Hardware Handshaking” on page 561
• Modem, described in Section 25.6.7 ”Modem Mode” on page 562
• ISO7816, described in Section 25.6.8 ”ISO7816 Mode” on page 563
• IrDA, described in Section 25.6.9 ”IrDA Mode” on page 566
• LIN Master, described in Section 25.6.10 ”LIN Mode” on page 568
• LIN Slave, described in Section 25.6.10 ”LIN Mode” on page 568
• SPI Master, described in Section 25.6.15 ”SPI Mode” on page 580
• SPI Slave, described in Section 25.6.15 ”SPI Mode” on page 580
The operating mode is selected by writing to the Mode field in the “Mode Register” (MR.MODE).
In addition, Synchronous or Asynchronous mode is selected by writing to the Synchronous
Mode Select bit in MR (MR.SYNC). By default, MR.MODE and MR.SYNC are both zero, and the
USART operates in Normal Asynchronous mode.
25.6.2 Basic Operation
To start using the USART, the user must perform the following steps:
1. Configure the baud rate by writing to the Baud Rate Generator Register (BRGR) as
described in ”Baud Rate Generator” on page 558
2. Select the operating mode by writing to the relevant fields in the Mode Regiser (MR)
3. Enable the transmitter and/or receiver, by writing a one to CR.TXEN and/or CR.RXEN
respectively
Table 25-3. MR.MODE
MR.MODE Mode of the USART
0x0 Normal
0x1 RS485
0x2 Hardware Handshaking
0x3 Modem
0x4 IS07816 Protocol: T = 0
0x6 IS07816 Protocol: T = 1
0x8 IrDA
0xA LIN Master
0xB LIN Slave
0xE SPI Master
0xF SPI Slave
Others Reserved