SC16C752BIBS Philips Semiconductors, SC16C752BIBS Datasheet - Page 7

• 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
6. Functional description
9397 750 14443
Product data
6.1 Trigger levels
6.2 Hardware flow control
The SC16C752B UART is pin-compatible with the SC16C2550 UART. It provides
more enhanced features. All additional features are provided through a special
enhanced feature register.
The UART will perform serial-to-parallel conversion on data characters received from
peripheral devices or modems, and parallel-to-parallel conversion on data characters
transmitted by the processor. The complete status of each channel of the
SC16C752B UART can be read at any time during functional operation by the
processor.
The SC16C752B can be placed in an alternate mode (FIFO mode) relieving the
processor of excessive software overhead by buffering received/transmitted
characters. Both the receiver and transmitter FIFOs can store up to 64 bytes
(including three additional bits of error status per byte for the receiver FIFO) and have
selectable or programmable trigger levels. Primary outputs RXRDY and TXRDY allow
signalling of DMA transfers.
The SC16C752B has selectable hardware flow control and software flow control.
Hardware flow control significantly reduces software overhead and increases system
efficiency by automatically controlling serial data flow using the RTS output and CTS
input signals. Software flow control automatically controls data flow by using
programmable Xon/Xoff characters.
The UART includes a programmable baud rate generator that can divide the timing
reference clock input by a divisor between 1 and (2
The SC16C752B provides independent selectable and programmable trigger levels
for both receiver and transmitter DMA and interrupt generation. After reset, both
transmitter and receiver FIFOs are disabled and so, in effect, the trigger level is the
default value of one byte. The selectable trigger levels are available via the FCR. The
programmable trigger levels are available via the TLR.
Hardware flow control is comprised of Auto-CTS and Auto-RTS. Auto-CTS and
Auto-RTS can be enabled/disabled independently by programming EFR[7:6].
With Auto-CTS, CTS must be active before the UART can transmit data.
Auto-RTS only activates the RTS output when there is enough room in the FIFO to
receive data and de-activates the RTS output when the RX FIFO is sufficiently full.
The halt and resume trigger levels in the TCR determine the levels at which RTS is
activated/deactivated.
If both Auto-CTS and Auto-RTS are enabled, when RTS is connected to CTS, data
transmission does not occur unless the receiver FIFO has empty space. Thus,
overrun errors are eliminated during hardware flow control. If not enabled, overrun
errors occur if the transmit data rate exceeds the receive FIFO servicing latency.
5 V, 3.3 V and 2.5 V dual UART, 5 Mbit/s (max.), with 64-byte FIFOs
Rev. 03 — 14 December 2004
16
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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SC16C752B
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