XR16C850CM EXAR [Exar Corporation], XR16C850CM Datasheet - Page 40

• Manufacturer Part Number: XR16C850CM
• Description: 2.97V TO 5.5V UART WITH 128-BYTE FIFO
• Manufacturer: EXAR [Exar Corporation]

XR16C850
2.97V TO 5.5V UART WITH 128-BYTE FIFO
EFR[5]: Special Character Detect Enable
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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 or hysteresis 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.
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EFR[7]: Auto CTS Flow Control Enable
Automatic CTS Flow Control.
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These registers are used as the programmable software flow control characters xoff1, xoff2, xon1, and xon2.
For more details, see
4.20
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.
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.
40
xr
REV. 2.3.1