sc16c852viet NXP Semiconductors, sc16c852viet Datasheet - Page 33

• Manufacturer Part Number: sc16c852viet
• Description: Sc16c852v 1.8 V Dual Uart, 5 Mbit/s Max. With 128-byte Fifos, Infrared Irda , And Xscale Vlio Bus Interface
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SC16C852V_4
Product data sheet
7.14 Enhanced Feature Register (EFR)
Enhanced features are enabled or disabled using this register.
Bit 0 through bit 4 provide single or dual character software flow control selection. When
the Xon1 and Xon2 and/or Xoff1 and Xoff2 modes are selected, the double 8-bit words
are concatenated into two sequential numbers.
Table 25.
[1]
Table 26.
Bit
7
6
5
4
3:0
Cont-3
0
1
0
Enhanced function control bits: IER[7:4], ISR[5:4], FCR[5:4] and MCR[7:5].
Symbol
EFR[7]
EFR[6]
EFR[5]
EFR[4]
EFR[3:0] Cont-3:0 Tx, Rx control. Logic 0 or cleared is the default condition.
Cont-2
0
0
1
Enhanced Feature Register bits description
Software flow control functions
Dual UART with 128-byte FIFOs, IrDA, and XScale VLIO bus interface
Description
Automatic CTS flow control.
Automatic RTS flow control. Automatic RTS may be used for hardware flow
control by enabling EFR[6]. When Auto-RTS is selected, an interrupt will be
generated when the receive FIFO is filled to the programmed trigger level and
RTS will go to a logic 1 at the next trigger level. RTS will return to a logic 0 when
data is unloaded below the next lower trigger level (programmed trigger level 1).
The state of this register bit changes with the status of the hardware flow
control. RTS functions normally when hardware flow control is disabled.
Special character detect.
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 SC16C852V
enhanced functions.
Combinations of software flow control can be selected by programming these
bits. See
Cont-1
X
X
X
logic 0 = automatic CTS flow control is disabled (normal default condition)
logic 1 = enable automatic CTS flow control. Transmission will stop when
CTS goes to a logical 1. Transmission will resume when the CTS signal
returns to a logical 0.
logic 0 = automatic RTS flow control is disabled (normal default condition)
logic 1 = enable automatic RTS flow control
logic 0 = special character detect disabled (normal default condition)
logic 1 = special character detect enabled. The SC16C852V 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).
logic 0 = disable/latch enhanced features
logic 1 = enables the enhanced functions
all enhanced features of the SC16C852V are enabled and user settings
stored during a reset will be restored.
Rev. 04 — 14 January 2008
Table
Cont-0
X
X
X
26.
TX, RX software flow controls
No transmit flow control
Transmit Xon1/Xoff1
Transmit Xon2/Xoff2
[1]
[1]
[1]
. When this bit is set to a logic 1,
SC16C852V
© NXP B.V. 2008. All rights reserved.
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