Datasheet

UART

SLLS519H—January 2010TUSB3410, TUSB3410I

7.1.5 Transmitter Flow Control

On reset (power up, USB, or soft reset) the transmitter defaults to the Xon state and the flow control is set to

mode-0 (flow control is disabled).

Table 7−2. Transmitter Flow-Control Modes

BIT 3 BIT 2 BIT 1 BIT 0

DSR CTS TXOA TXOF

All flow control is disabled 0 0 0 0

Xon/Xoff flow control is enabled 0 0 0 1

Xon on any/ Xoff flow control 0 0 1 0

Not permissible (see Note 9) X X 1 1

CTS flow control 0 1 0 0

Combination flow control (see Note 10) 0 1 0 1

Combination flow control 0 1 1 0

DSR flow control 1 0 0 0

1 0 0 1

1 0 1 0

Combination flow control

1 1 0 0

Combination

flow

control

1 1 0 1

1 1 1 0

NOTES: 9. This is a nonpermissible combination. If used, TXOA and TXOF are cleared.

10. Combination example: Transmitter stops when either CTS or Xoff is detected. Transmitter resumes when both CTS is negated and

Xon is detected.

Table 7−3. Receiver Flow-Control Possibilities

MODE

BIT 6 BIT 5 BIT 4

MODE

DTR RTS RXOF

0 All flow control is disabled 0 0 0

1 Xon/Xoff flow control is enabled 0 0 1

2 RTS flow control 0 1 0

3 Combination flow control (see Note 11) 0 1 1

4 DTR flow control 1 0 0

5 Combination flow control 1 0 1

6 Combination flow control (see Note 12) 1 1 0

7 Combination flow control 1 1 1

NOTES: 11. Combination example: Both RTS is asserted and Xoff transmitted when the FIFO is full. Both RTS is deasserted and Xon is

transmitted when the FIFO is empty.

12. Combination example: Both DTR and RTS are asserted when the FIFO is full. Both DTR and RTS are deasserted when the FIFO

is empty.