XR16M2551 Datasheet, PDF (35/51 Pages) Exar Corporation – HIGH PERFORMANCE LOW VOLTAGE DUART WITH 16-BYTE FIFO AND POWERSAVE FEATURE

XR16M2551
REV. 1.0.2
HIGH PERFORMANCE LOW VOLTAGE DUART WITH 16-BYTE FIFO AND POWERSAVE FEATURE
4.12 Device Identification Register (DVID) - Read Only
This register contains the device ID (0x02 for XR16M2551). Prior to reading this register, DLL and DLM should
be set to 0x00 (DLD = 0xXX).
4.13 Device Revision Register (DREV) - Read Only
This register contains the device revision information. For example, 0x01 means revision A. Prior to reading
this register, DLL and DLM should be set to 0x00 (DLD = 0xXX).
4.14 Enhanced Feature Register (EFR)
Enhanced features are enabled or disabled using this register. Bit 0-3 provide single or dual consecutive
character software flow control selection (see Table 15). When the Xon1 and Xon2 and Xoff1 and Xoff2 modes
are selected, the double 8-bit words are concatenated into two sequential characters. Caution: note that
whenever changing the TX or RX flow control bits, always reset all bits back to LOW (disable) before
programming a new setting.
EFR[3:0]: Software Flow Control Select
Single character and dual sequential characters software flow control is supported. Combinations of software
flow control can be selected by programming these bits.
EFR BIT-3
CONT-3
0
0
1
0
1
X
X
X
1
0
1
0
TABLE 15: SOFTWARE FLOW CONTROL FUNCTIONS
EFR BIT-2
CONT-2
EFR BIT-1
CONT-1
EFR BIT-0
CONT-0
TRANSMIT AND RECEIVE SOFTWARE FLOW CONTROL
0
0
0
No TX and RX flow control (default and reset)
0
X
X
No transmit flow control
0
X
X
Transmit Xon1, Xoff1
1
X
X
Transmit Xon2, Xoff2
1
X
X
Transmit Xon1 and Xon2, Xoff1 and Xoff2
X
0
0
No receive flow control
X
1
0
Receiver compares Xon1, Xoff1
X
0
1
Receiver compares Xon2, Xoff2
0
1
1
Transmit Xon1, Xoff1
Receiver compares Xon1 or Xon2, Xoff1 or Xoff2
1
1
1
Transmit Xon2, Xoff2
Receiver compares Xon1 or Xon2, Xoff1 or Xoff2
1
1
1
Transmit Xon1 and Xon2, Xoff1 and Xoff2
Receiver compares Xon1 and Xon2, Xoff1 and Xoff2
0
1
1
No transmit flow control
Receiver compares Xon1 and Xon2, Xoff1 and Xoff2
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