SC16C554BIB64 PHILIPS [NXP Semiconductors], SC16C554BIB64 Datasheet - Page 18

• Manufacturer Part Number: SC16C554BIB64
• Description: 5 V, 3.3 V and 2.5 V quad UART, 5 Mbit/s (max.) with 16-byte FIFOs
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 13133
Product data sheet
Fig 10. RTS functional timing waveforms, RCV FIFO trigger level = 14 bytes
(RD RBR)
(1) RTS is de-asserted when the receiver receives the first data bit of the sixteenth byte. The receive FIFO is full after finishing
(2) RTS is asserted again when there is at least one byte of space available and no incoming byte is in processing, or there is
(3) When the receive FIFO is full, the first receive buffer register read re-asserts RTS.
RTS
IOR
RX
the sixteenth byte.
more than one byte of space available.
6.5 Hardware/software and time-out interrupts
6.6 Programmable baud rate generator
byte 14
Following a reset, if the transmitter interrupt is enabled, the SC16C554B/554DB will issue
an interrupt to indicate that the Transmit Holding Register is empty. This interrupt must be
serviced prior to continuing operations. The LSR register provides the current singular
highest priority interrupt only. Only after servicing the higher pending interrupt will the
lower priority interrupt(s) be reflected in the status register. Servicing the interrupt without
investigating further interrupt conditions can result in data errors.
When two interrupt conditions have the same priority, it is important to service these
interrupts correctly. Receive Data Ready and Receive Time Out have the same interrupt
priority (when enabled by IER[0]). The receiver issues an interrupt after the number of
characters have reached the programmed trigger level. In this case, the
SC16C554B/554DB FIFO may hold more characters than the programmed trigger level.
Following the removal of a data byte, the user should re-check LSR[0] for additional
characters. A Receive Time Out will not occur if the receive FIFO is empty. The time-out
counter is reset at the center of each stop bit received or each time the receive holding
register (RHR) is read. The actual time-out value is 4 character time.
In the 16 mode for the PLCC68 package, the system/board designer can optionally
provide software controlled 3-state interrupt operation. This is accomplished by INTSEL
and MCR[3]. When INTSEL interface pin is left open or made a logic 0, MCR[3] controls
the 3-state interrupt outputs, INTA to INTD. When INTSEL is a logic 1, MCR[3] has no
effect on the INTA to INTD outputs, and the package operates with interrupt outputs
enabled continuously.
The SC16C554B/554DB supports high speed modem technologies that have increased
input data rates by employing data compression schemes. For example, a 33.6 kbit/s
modem that employs data compression may require a 115.2 kbit/s input data rate.
A 128.0 kbit/s ISDN modem that supports data compression may need an input data rate
of 460.8 kbit/s.
RTS released after the
first data bit of byte 16
byte 15
5 V, 3.3 V and 2.5 V quad UART, 5 Mbit/s (max.) with 16-byte FIFOs
Rev. 01 — 9 February 2005
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byte 16
Stop
SC16C554B/554DB
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
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