xr16v564 Exar Corporation, xr16v564 Datasheet - Page 37

• Manufacturer Part Number: xr16v564
• Description: 2.25v To 3.6v Quad Uart With 32-byte Fifo
• Manufacturer: Exar Corporation

REV. 1.0.1
EFR[4]: Enhanced Function Bits Enable
Enhanced function control bit. This bit enables IER bits 4-7, ISR bits 4-5, FCR bits 4-5, MCR bits 5-7, and DLD
to be modified. After modifying any enhanced bits, EFR bit-4 can be set to a LOW to latch the new values. This
feature prevents legacy software from altering or overwriting the enhanced functions once set. Normally, it is
recommended to leave it enabled, HIGH.
•
•
EFR[5]: Special Character Detect Enable
•
•
Logic 0 = modification disable/latch enhanced features. IER bits 4-7, ISR bits 4-5, FCR bits 4-5, MCR bits 5-
7, and DLD are saved to retain the user settings. After a reset, the IER bits 4-7, ISR bits 4-5, FCR bits 4-5,
and MCR bits 5-7, and DLD are set to a LOW to be compatible with ST16C550 mode (default).
Logic 1 = Enables the above-mentioned register bits to be modified by the user.
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.
EFR
C
ONT
X
X
X
0
0
1
0
1
1
0
1
0
BIT
-3
-3
EFR
C
ONT
X
X
X
0
0
0
1
1
0
1
1
0
BIT
-2
-2
T
ABLE
EFR
C
ONT
16: S
X
X
X
X
0
0
1
0
1
1
1
1
BIT
-1
-1
OFTWARE
EFR
C
ONT
0
X
X
X
X
0
0
1
1
1
1
1
F
BIT
37
LOW
-0
-0
2.25V TO 3.6V QUAD UART WITH 32-BYTE FIFO
C
No TX and RX flow control (default and reset)
No transmit flow control
Transmit Xon1, Xoff1
Transmit Xon2, Xoff2
Transmit Xon1 and Xon2, Xoff1 and Xoff2
No receive flow control
Receiver compares Xon1, Xoff1
Receiver compares Xon2, Xoff2
Transmit Xon1, Xoff1
Receiver compares Xon1 or Xon2, Xoff1 or Xoff2
Transmit Xon2, Xoff2
Receiver compares Xon1 or Xon2, Xoff1 or Xoff2
Transmit Xon1 and Xon2, Xoff1 and Xoff2,
Receiver compares Xon1 and Xon2, Xoff1 and Xoff2
No transmit flow control,
Receiver compares Xon1 and Xon2, Xoff1 and Xoff2
ONTROL
T
RANSMIT AND
F
UNCTIONS
R
ECEIVE
S
OFTWARE
XR16V564/564D
F
LOW
C
ONTROL