SC28L201A1DGG,118 NXP Semiconductors, SC28L201A1DGG,118 Datasheet - Page 35

• Manufacturer Part Number: SC28L201A1DGG,118
• Description: IC UART W/FIFO 48-TSSOP
• Manufacturer: NXP Semiconductors
• Series: IMPACTr

Specifications of SC28L201A1DGG,118

• Features: False-start Bit Detection
• Number Of Channels: 2, DUART
• Fifo's: 256 Byte
• Voltage - Supply: 3.3V, 5V
• With Parallel Port: Yes
• With Auto Flow Control: Yes
• With False Start Bit Detection: Yes
• With Modem Control: Yes
• With Cmos: Yes
• Mounting Type: Surface Mount
• Package / Case: 48-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 935277824118; SC28L201A1DGG-T; SC28L201A1DGG-T

Philips Semiconductors
9397 750 13138
Product data sheet
7.4.10.5 Receiver mode
7.4.10.6 Auto-receive and transmit (most efficient)
Since the receiving FIFO resources in the UART are limited, some means of controlling a
remote transmitter is desirable in order to lessen the probability of receiver overrun. The
UART provides two methods of controlling the data flow. There is a hardware-assisted
means of accomplishing control, the so-called out-of-band flow control, and an in-band
flow control method.
The out-of-band flow control is implemented through the CTSN-RTSN signaling via the
I/O ports. The operation of these hardware handshake signals is described in the receiver
and transmitter discussions.
In-band flow control is a protocol for controlling a remote transmitter by embedding special
characters within the message stream, itself. Two characters, Xon and Xoff, which do not
represent normal printable character take on flow control definitions when the Xon/Xoff
capability is enabled. Flow control characters received may be used to gate the channel
transmitter on and off. This activity is referred to as Auto-transmitter mode. To protect the
channel receiver from overrun, fixed fill levels (hardware set at 240 characters) of the
RxFIFO may be employed to automatically insert Xon/Xoff characters in the transmitters
data stream. This mode of operation is referred to as Auto-receiver mode. Commands
issued by the host CPU via the CR can simulate all these conditions.
This is a combination of both modes.
Remark: Xon/Xoff characters: The Xon/Xoff character with errors will be accepted as
valid. The user has the option sending or not sending these characters to the FIFO. Error
bits associated with Xon/Xoff will be stored normally to the receiver FIFO.
The channel’s transmitter may be programmed to automatically transmit an Xoff character
without host CPU intervention when the RxFIFO fill level exceeds a fixed limit (240). In this
mode it will transmit an Xon character when the RxFIFO level drops below a second fixed
limit (16). A character from the TxFIFO that has been loaded into the TXD shift register
will continue to transmit. Character(s) in the TxFIFO that have not been loaded to the
transmitter shift register are unaffected by the Xon or Xoff transmission. They will be
transmitted after the Xon/Xoff activity concludes.
If the fill level condition that initiates Xon activity negates before the flow control character
can begin transmission, the transmission of the flow control character will not occur.
Hardware keeps track of Xoff characters sent that are not rescinded by an Xon. This logic
is reset by writing MR3[3:2] to ‘00’. If the user drops out of Auto-receiver mode while the
XISR shows Xoff as the last character sent, the Xon/Xoff logic would not automatically
send the negating Xon.
The disable CRTX command (of the Command Register, 0x18) can be used to cleanly
terminate any pending CRTX commands.
Remark: In no case will an Xon/Xoff character transmission be aborted. Once the
character is loaded into the TX Shift Register, transmission continues until completion or a
chip reset or transmitter reset is encountered. The kill CRTX command has no effect in
either of the Auto modes.
Rev. 01 — 31 October 2005
3.3 V, 5 V UART, 3.125 Mbit/s, with 256-byte FIFO
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
SC28L201
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