SC16C550BIBS-F NXP Semiconductors, SC16C550BIBS-F Datasheet - Page 11

• Manufacturer Part Number: SC16C550BIBS-F
• Manufacturer: NXP Semiconductors

Specifications of SC16C550BIBS-F

• Transmit Fifo: 16Byte
• Receive Fifo: 16Byte
• Transmitter And Receiver Fifo Counter: Yes
• Operating Supply Voltage (max): 5.5V
• Mounting: Surface Mount
• Pin Count: 32
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Number Of Channels: 1
• Lead Free Status / RoHS Status: Compliant

NXP Semiconductors
SC16C550B_5
Product data sheet
Fig 6.
D7 to D0
Autoflow control (auto-RTS and auto-CTS) example
6.3.1 Auto-RTS
6.3.2 Auto-CTS
6.3 Autoflow control
Autoflow control is comprised of auto-CTS and auto-RTS (see
the CTS input must be active before the transmitter FIFO can emit data. With auto-RTS,
RTS becomes active when the receiver needs more data and notifies the sending serial
device. When RTS is connected to CTS, data transmission does not occur unless the
receiver FIFO has space for the data; thus, overrun errors are eliminated using UART 1
and UART 2 from a SC16C550B with the autoflow control enabled. If not, overrun errors
occur when the transmit data rate exceeds the receiver FIFO read latency.
Auto-RTS data flow control originates in the receiver timing and control block (refer to
Figure 1 “Block diagram of
trigger level (see
or 8 (see
UART may send an additional byte after the trigger level is reached (assuming the
sending UART has another byte to send) because it may not recognize the de-assertion of
RTS until after it has begun sending the additional byte. RTS is automatically reasserted
once the RX FIFO is emptied by reading the receiver buffer register. When the trigger level
is 14 (see
present on the RX line. RTS is reasserted when the RX FIFO has at least one available
byte space.
The transmitter circuitry checks CTS before sending the next data byte (see
When CTS is active, it sends the next byte. To stop the transmitter from sending the
following byte, CTS must be released before the middle of the last stop bit that is currently
being sent (see
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.
FIFO
FIFO
TX
RX
UART 1
Figure
Figure
SERIAL TO
TO SERIAL
PARALLEL
PARALLEL
CONTROL
CONTROL
FLOW
FLOW
Figure
8), RTS is de-asserted. With trigger levels of 1, 4, and 8, the sending
Figure
9), RTS is de-asserted after the first data bit of the 16th character is
Rev. 05 — 1 October 2008
7). The auto-CTS function reduces interrupts to the host system.
RTS
CTS
6). When the receiver FIFO level reaches a trigger level of 1, 4,
RX
TX
SC16C550B”) and is linked to the programmed receiver FIFO
TX
CTS
RX
RTS
5 V, 3.3 V and 2.5 V UART with 16-byte FIFOs
TO SERIAL
SERIAL TO
PARALLEL
PARALLEL
CONTROL
CONTROL
FLOW
FLOW
UART 2
Figure
FIFO
FIFO
SC16C550B
RX
TX
6). With auto-CTS,
002aaa228
© NXP B.V. 2008. All rights reserved.
Figure
D7 to D0
11 of 48
6).