SC16C550 Datasheet, PDF (31/52 Pages) NXP Semiconductors – Universal Asynchronous Receiver/Transmitter (UART) with 16-byte FIFO and infrared (IrDA) encoder/decoder

Philips Semiconductors
SC16C550
UART with 16-byte FIFO and IrDA encoder/decoder
Table 21: Enhanced Feature Register bits description…continued
Bit Symbol Description
5
EFR[5] Special Character Detect.
Logic 0 = Special character detect disabled (normal default condition).
Logic 1 = Special character detect enabled. The SC16C550 compares
each incoming receive character with Xoff2 data. If a match exists, the
received data will be transferred to FIFO and ISR[4] will be set to
indicate detection of special character. Bit-0 in the X-registers
corresponds with the LSB bit for the receive character. When this feature
is enabled, the normal software flow control must be disabled (EFR[3-0]
must be set to a logic 0).
4
EFR[4] Enhanced function control bit. The content of IER[7-4], ISR[5-4], FCR[5-4],
and MCR[7-5] can be modified and latched. After modifying any bits in the
enhanced registers, EFR[4] can be set to a logic 0 to latch the new values.
This feature prevents existing software from altering or overwriting the
SC16C550 enhanced functions.
Logic 0 = Disable (normal default condition).
Logic 1 = Enable.
3-0 EFR[3-0] Cont-3-0 Tx, Rx control. Logic 0 or cleared is the default condition.
Combinations of software flow control can be selected by programming
these bits. See Table 22.
Table 22: Software flow control functions^[1]
Cont-3 Cont-2 Cont-1 Cont-0 TX, RX software flow controls
0
0
X
X
No transmit flow control
1
0
X
X
Transmit Xon1/Xoff1
0
1
X
X
Transmit Xon2/Xoff2
1
1
X
X
Transmit Xon1 and Xon2/Xoff1 and Xoff2
X
X
0
0
No receive flow control
X
X
1
0
Receiver compares Xon1/Xoff1
X
X
0
1
Receiver compares Xon2/Xoff2
1
0
1
1
Transmit Xon1/Xoff1
Receiver compares Xon1 and Xon2, Xoff1 and Xoff2
0
1
1
1
Transmit Xon2/Xoff2
Receiver compares Xon1 and Xon2/Xoff1 and Xoff2
1
1
1
1
Transmit Xon1 and Xon2/Xoff1 and Xoff2
Receiver compares Xon1 and Xon2/Xoff1 and Xoff2
[1] When using a software flow control the Xon/Xoff characters cannot be used for data transfer.
9397 750 11619
Product data
Rev. 05 — 19 June 2003
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
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