Manual

171

ATmega169V/L

2514A–AVR–08/02

USART Control and Status

• Bit 6 – UMSEL: USART Mode Select

This bit selects between asynchronous and synchronous mode of operation.

• Bit 5:4 – UPM1:0: Parity Mode

These bits enable and set type of parity generation and check. If enabled, the Transmit-

ter will automatically generate and send the parity of the transmitted data bits within

each frame. The Receiver will generate a parity value for the incoming data and com-

pare it to the UPM0 setting. If a mismatch is detected, the UPE Flag in UCSRA will be

set.

• Bit 3 – USBS: Stop Bit Select

This bit selects the number of stop bits to be inserted by the Transmitter. The Receiver

ignores this setting.

Bit 76543210

– UMSEL UPM1 UPM0 USBS UCSZ1 UCSZ0 UCPOL UCSRC

Read/Write R R/W R/W R/W R/W R/W R/W R/W

InitialValue00000110

Table 74. UMSEL Bit Settings

UMSEL Mode

0 Asynchronous Operation

1 Synchronous Operation

Table 75. UPM Bits Settings

UPM1 UPM0 Parity Mode

0 0 Disabled

01Reserved

1 0 Enabled, Even Parity

1 1 Enabled, Odd Parity

Table 76. USBS Bit Settings

USBS Stop Bit(s)

01-bit

12-bit