SC16C752BIBS Philips Semiconductors, SC16C752BIBS Datasheet - Page 9

• Manufacturer Part Number: SC16C752BIBS
• Description: 5 V/ 3.3 V and 2.5 V dual UART/ 5 Mbit/s (max.)/ with 64-byte FIFOs
• Manufacturer: Philips Semiconductors

Philips Semiconductors
9397 750 14443
Product data
Fig 6. CTS functional timing.
(1) When CTS is LOW, the transmitter keeps sending serial data out.
(2) When CTS goes HIGH before the middle of the last stop bit of the current byte, the transmitter finishes sending the current
(3) When CTS goes from HIGH to LOW, the transmitter begins sending data again.
byte, but is does not send the next byte.
CTS
TX
6.2.2 Auto-CTS
6.3 Software flow control
The transmitter circuitry checks CTS before sending the next data byte. When CTS is
active, the transmitter sends the next byte. To stop the transmitter from sending the
following byte, CTS must be deasserted before the middle of the last stop bit that is
currently being sent. The auto-CTS function reduces interrupts to the host system.
When flow control is enabled, CTS level changes do not trigger host interrupts
because the device automatically controls its own transmitter. Without auto-CTS, the
transmitter sends any data present in the transmit FIFO and a receiver overrun error
may result.
Software flow control is enabled through the enhanced feature register and the
modem control register. Different combinations of software flow control can be
enabled by setting different combinations of EFR[3:0].
control options.
Table 3:
EFR[3]
0
1
0
1
X
X
X
1
0
1
Start
EFR[2]
0
0
1
1
X
X
X
0
1
1
Software flow control options (EFR[0:3])
byte 0 to 7
5 V, 3.3 V and 2.5 V dual UART, 5 Mbit/s (max.), with 64-byte FIFOs
Rev. 03 — 14 December 2004
EFR[1]
X
X
X
X
0
1
0
1
1
1
Stop
EFR[0]
X
X
X
X
0
0
1
1
1
1
TX, RX software flow controls
no transmit flow control
transmit Xon1, Xoff1
transmit Xon2, Xoff2
transmit Xon1, Xon2, Xoff1, Xoff2
no receive flow control
receiver compared Xon1, Xoff1
receiver compares Xon2, Xoff2
transmit Xon1, Xoff1
receiver compares Xon1 and Xon2, Xoff1 and Xoff2
transmit Xon2, Xoff2
receiver compares Xon1 and Xon2, Xoff1 and Xoff2
transmit Xon1, Xon2, Xoff1, Xoff2
receiver compares Xon1 and Xon2, Xoff1 and Xoff2
Start
byte 0 to 7
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
Table 3
SC16C752B
shows software flow
002aaa227
Stop
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