SC16IS762 Philips Semiconductors, SC16IS762 Datasheet - Page 8

• Manufacturer Part Number: SC16IS762
• Description: (SC16IS752 / SC16IS762) Dual UART
• Manufacturer: Philips Semiconductors

NXP Semiconductors
7. Functional description
SC16IS752_SC16IS762_6
Product data sheet
7.1 Trigger levels
7.2 Hardware flow control
The UART will perform serial-to-I
peripheral devices or modems, and I
transmitted by the host. The complete status of the SC16IS752/SC16IS762 UART can be
read at any time during functional operation by the host.
The SC16IS752/SC16IS762 can be placed in an alternate mode (FIFO mode) relieving
the host of excessive software overhead by buffering received/transmitted characters.
Both the receiver and transmitter FIFOs can store up to 64 characters (including three
additional bits of error status per character for the receiver FIFO) and have selectable or
programmable trigger levels.
The SC16IS752/SC16IS762 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 SC16IS752/SC16IS762 provides independently selectable and programmable trigger
levels for both receiver and transmitter interrupt generation. After reset, both transmitter
and receiver FIFOs are disabled and so, in effect, the trigger level is the default value of
one character. The selectable trigger levels are available via the FIFO Control Register
(FCR). The programmable trigger levels are available via the Trigger Level Register (TLR).
If TLR bits are cleared, then selectable trigger level in FCR is used. If TLR bits are not
cleared, then programmable trigger level in TLR is used.
Hardware flow control is comprised of Auto-CTS and Auto-RTS (see
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 Transmission Control Register (TCR) determine the levels at
which RTS is activated/deactivated. If TCR bits are cleared, then selectable trigger levels
in FCR are used in place of TCR.
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.
Rev. 06 — 19 December 2006
Dual UART with I
2
C-bus conversion on data characters received from
2
C-bus-to-serial conversion on data characters
2
SC16IS752/SC16IS762
C-bus/SPI interface, 64-byte FIFOs, IrDA SIR
16
1).
Figure
© NXP B.V. 2006. All rights reserved.
4). Auto-CTS
8 of 59