XR16L580 Exar Corporation, XR16L580 Datasheet - Page 14

• Manufacturer Part Number: XR16L580
• Description: Smallest 2.25 to 5.5V Uart With 16-Byte Fifo And Power-save
• Manufacturer: Exar Corporation

XR16L580
SMALLEST 2.25V TO 5.5V UART WITH 16-BYTE FIFO AND POWERSAVE
Automatic RTS hardware flow control is used to prevent data overrun to the local receiver FIFO. The RTS#
output is used to request remote unit to suspend/resume data transmission. The auto RTS flow control
features is enabled to fit specific application requirement (see
- Enable auto RTS flow control using EFR bit-6.
- The auto RTS function must be started by asserting RTS# output pin (MCR bit-1 to logic 1 after it is enabled).
- Enable RTS interrupt through IER bit-6 (after setting EFR bit-4). The UART issues an interrupt when the
RTS# pin makes a transition from low to high: ISR bit-5 will be set to logic 1.
The L580 has a new feature that provides flow control trigger hysteresis while maintaining compatibility with
the ST16C550 UART. With the Auto RTS function enabled, an interrupt is generated when the receive FIFO
reaches the programmed RX trigger level. The RTS# pin will not be forced to a logic 1 (RTS off), until the
receive FIFO reaches one trigger level above the programmed trigger level in the trigger table
RTS# pin will return to a logic 0 after the RX FIFO is unloaded to one trigger level lower than the programmed
trigger level. This is described in
accept data until the receive FIFO gets full. The Auto RTS function is initiated when the RTS# output pin is
asserted to a logic 0 (RTS On).
Automatic CTS flow control is used to prevent data overrun to the remote receiver FIFO. The CTS# input is
monitored to suspend/restart the local transmitter. The auto CTS flow control feature is selected to fit specific
application requirement (see
- Enable auto CTS flow control using EFR bit-7.
- Enable CTS interrupt through IER bit-7 (after setting EFR bit-4). The UART issues an interrupt when the
CTS# pin is de-asserted (logic 1): ISR bit-5 will be set to 1, and UART will suspend transmission as soon as
the stop bit of the character in process is shifted out. Transmission is resumed after the CTS# input is re-
asserted (logic 0), indicating more data may be sent.
2.12
2.13
2.14
Auto RTS (Hardware) Flow Control
Auto RTS Hysteresis
Auto CTS Flow Control
Figure
Figure
11):
11. Under the above described conditions, the L580 will continue to
14
Figure
11):
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(Table
REV. 1.2.0
8). The