xr16l2550im Exar Corporation, xr16l2550im Datasheet - Page 32

• Manufacturer Part Number: xr16l2550im
• Description: Industry Smallest Package Uart With 2.25v To 5.5v Operation
• Manufacturer: Exar Corporation

XR16L2550
LOW VOLTAGE DUART WITH 16-BYTE FIFO
EFR[5]: Special Character Detect Enable
•
•
EFR[6]: Auto RTS Flow Control Enable
RTS# output may be used for hardware flow control by setting EFR bit-6 to logic 1. When Auto RTS is
selected, an interrupt will be generated when the receive FIFO is filled to the programmed trigger level and
RTS de-asserts to a logic 1 at the next upper trigger level. RTS# will return to a logic 0 when FIFO data falls
below the next lower trigger level. The RTS# output must be asserted (logic 0) before the auto RTS can take
effect. RTS# pin will function as a general purpose output when hardware flow control is disabled.
•
•
EFR[7]: Auto CTS Flow Control Enable
Automatic CTS Flow Control.
•
•
These registers are used as the programmable software flow control characters XOFF1, XOFF2, XON1, and
XON2. For more details, see
4.15
Logic 0 = Special Character Detect Disabled (default).
Logic 1 = Special Character Detect Enabled. The UART compares each incoming receive character with
data in Xoff-2 register. If a match exists, the receive data will be transferred to FIFO and ISR bit-4 will be set
to indicate detection of the special character. Bit-0 corresponds with the LSB bit of the receive character. If
flow control is set for comparing Xon1, Xoff1 (EFR [1:0]= ‘10’) then flow control and special character work
normally. However, if flow control is set for comparing Xon2, Xoff2 (EFR[1:0]= ‘01’) then flow control works
normally, but Xoff2 will not go to the FIFO, and will generate an Xoff interrupt and a special character
interrupt, if enabled via IER bit-5. Special character interrupts are cleared automatically after the next
received character.
Logic 0 = Automatic RTS flow control is disabled (default).
Logic 1 = Enable Automatic RTS flow control.
Logic 0 = Automatic CTS flow control is disabled (default).
Logic 1 = Enable Automatic CTS flow control. Data transmission stops when CTS# input de-asserts to logic
1. Data transmission resumes when CTS# returns to a logic 0.
Software Flow Control Registers (XOFF1, XOFF2, XON1, XON2) - Read/Write
Table
6.
32
REV. 1.1.2