SC16C554 Datasheet, PDF (34/55 Pages) NXP Semiconductors – Quad UART with 16-byte FIFO and infrared (IrDA) encoder/decoder

Philips Semiconductors
SC16C554/554D
Quad UART with 16-byte FIFO and infrared (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 SC16C554/554D
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], and
MCR[6] 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 SC16C554/554D 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 software flow control the Xon/Xoff characters cannot be used for data transfer.
9397 750 13132
Product data
Rev. 05 — 10 May 2004
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
34 of 55