Datasheet
9397 750 14965 © Koninklijke Philips Electronics N.V. 2005. All rights reserved.
Product data sheet Rev. 02 — 20 June 2005 16 of 58
Philips Semiconductors
SC16C654B/654DB
5 V, 3.3 V and 2.5 V quad UART, 5 Mbit/s (max.) with 64-byte FIFOs
6.1 Interface options
Two user interface modes are selectable for the PLCC68 package. These interface modes
are designated as the ‘16 mode’ and the ‘68 mode’. This nomenclature corresponds to the
early 16C454/554 and 68C454/554 package interfaces respectively.
6.1.1 The 16 mode interface
The 16 mode configures the package interface pins for connection as a standard
16 series (Intel) device and operates similar to the standard CPU interface available on
the 16C454/554. In the 16 mode (pin 16/68 = logic 1), each UART is selected with
individual chip select (CSx) pins, as shown in Table 3.
6.1.2 The 68 mode interface
The 68 mode configures the package interface pins for connection with Motorola, and
other popular microprocessor bus types. The interface operates similar to the
68C454/554. In this mode, the SC16C654B/654DB decodes two additional addresses,
A3-A4, to select one of the four UART ports. The A[3:4] address decode function is used
only when in the 68 mode (16/68 = logic 0), and is shown in Table 4.
Table 3: Serial port channel selection, 16 mode interface
CSA CSB CSC CSD UART channel
1111none
0111A
1011B
1101C
1110D
Table 4: Serial port channel selection, 68 mode interface
CS A4 A3 UART channel
1 n/a n/a none
000A
001B
010C
011D