sc16c850iet NXP Semiconductors, sc16c850iet Datasheet - Page 32

• Manufacturer Part Number: sc16c850iet
• Description: Sc16c850 2.5 V To 3.3 V Uart, 5 Mbit/s Max. With 128-byte Fifos, Infrared Irda , And 16 Mode Or 68 Mode Parallel Bus Interface
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SC16C850_1
Product data sheet
7.14 Enhanced Feature Register (EFR)
Enhanced features are enabled or disabled using this register.
Bits 0 through 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 23.
[1]
Bit
7
6
5
4
3:0
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.
Enhanced Feature Register bits description
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 SC16C850 enhanced
functions.
Combinations of software flow control can be selected by programming these
bits. See
2.5 V to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
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 pin 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 SC16C850 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
Rev. 01 — 10 January 2008
Table
24.
[1]
[1]
. (Normal default condition.)
.
SC16C850
© NXP B.V. 2008. All rights reserved.
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