NS486SXF Datasheet, PDF (8/44 Pages) National Semiconductor (TI) – NS486TMSXF Optimized 32-Bit 486-Class Controller with On-Chip Peripherals for Embedded Systems

1 0 System Overview (Continued)
When the CPU is in idle mode the BIU is designed to mimic
the CPU during DMA interchanges between memory and
peripherals By responding to DRQs and generating DACK
and HOLDA signals as required the BIU eliminates the
need to reactivate the CPU during such transfers as screen
updates from memory to the LCD controller This gives the
designer added flexibility in conserving power while main-
taining basic system functions
1 5 OTHER ON-BOARD PERIPHERALS
In addition to those peripherals and system control ele-
ments needed for System Service Elements the NS486SXF
also includes a number of I O controllers and resources
that make implementing a complete embedded system pos-
sible with just a single-chip NS486SXF controller These in-
clude an IEEE 1284 Extended Capabilities Port a serial
UART port a LCD controller a PCMCIA interface and a
MICROWIRE or Access bus synchronous serial bus inter-
face In addition unused I O controllers free up their I O
pins for general purpose use
1 5 1 Reconfigurable I O Lines
The NS486SXF supports reconfigurable I O For example if
the UART ECP Parallel Port LCD or PCMCIA functions are
not being used the I O pins associated with them can be
reconfigured as general purpose bidirectional I O pins Up
to 29 pins can be reconfigured for this purpose This capa-
bility makes the NS486SXF extremely versatile and ideal for
supporting different end product configurations with a single
NS486SXF device
1 5 2 IEEE 1284 Bidirectional Port
The NS486SXF parallel port is a multifunction 8-bit parallel
port that is compatible with the IEEE 1284 bidirectional par-
allel port standard The operation of the parallel port is set
by the content of the NS486SXF parallel port I O control
registers The port can operate in one of two modes a stan-
dard parallel port mode (PC compatible) or a full Extended
Capabilities Port (ECP) mode The NS486SXF ECP port can
support both Host and Slave ECP mode In slave mode the
NS486SXF becomes a versatile microprocessor for parallel
I O peripheral devices
1 5 3 PCMCIA Interface
The NS486SXF PCMCIA interface supports the direct con-
nection of a single PCMCIA 2 0 IC card Exchange Card
Architecture (ExCA release 1 50) compatibility and eXecute
In Place (XIP) capability is also provided
Accessing the PCMCIA interface switches the external bus
automatically into the PCMCIA mode and permits Memory
Window Mapping and Address Offset to be handled inside
the NS486SXF device Power management and ‘‘hot’’ card
insertion removal options can be implemented using exter-
nal buffering if required
1 5 4 MICROWIRE Access bus Interface
The NS486SXF MICROWIRE Access bus interface pro-
vides for full support of either the three-wire MICROWIRE or
the two-wire Access bus serial interfaces MICROWIRE has
an alternate clock phasing option that supports the SPI bus
protocol as well These industry standard interfaces permit
easy interfacing to a wide range of low-cost specialty mem-
ories and I O devices These include EEPROMs SRAMs
timers clock chips A D converters D A converters and
peripheral device drivers
1 5 5 UART Serial Port
The NS486SXF UART provides complete NS16550 (PC
standard) serial communications port compatibility including
the performance enhancing 16-byte deep FIFO It performs
serial-to-parallel conversion from external devices to the
NS486SXF and parallel-to-serial conversion from the
NS486SXF to external peripherals Full modem control can
be supported
A serial IrDA v1 0 and HP-SIR (infrared) mode is also sup-
ported making possible low-cost wireless communications
between an NS486SXF-based system and other wireless
infrared systems
1 5 6 LCD Controller
The NS486SXF LCD controller is capable of controlling a
variety of monochrome supertwist LCD configurations in-
cluding 320x240 320x200 and 480x320 black and white or
grayscale graphics LCD modules equipped with self-con-
tained screen drivers It uses a video frame buffer in system
DRAM with either a 1- or 2-bit per pixel grayscale A 60 Hz
to 90 Hz frame refresh rate is supported Special controls
permit the fine tuning of display characteristics to precisely
optimize visual display quality
1 6 ICE SUPPORT
National Semiconductor has worked closely with Microtek
International to provide hardware in-circuit emulator support
for the NS486SXF The Microtek product (PowerPack EA-
NS486) uses a special bondout version of the NS486SXF to
deliver a full-featured hardware emulator that is capable of
tracing on chip activity including peripheral interrupt and
I O activity The emulator runs at full speed and supports
overlay memory and multiple triggers
1 7 OTHER ISSUES
NS486SXF provides a comprehensive set of on-board pe-
ripherals Also it is designed to easily interface to external
peripherals In addition to this ISA-like bus which supports
ISA-compatible peripherals the NS486SXF provides an in-
terface to an external master with a shared memory space
The external master or auxiliary processor interface allows
low cost interfacing to shared external memory belonging to
other external masters (including another NS486SXF con-
troller)
To program the resources of the NS486SXF a set of inter-
nal control registers exists These registers provide precise
control over all internal resources and the setup of external
NS486SXF control signals It is the designer’s responsibility
to ensure the proper initialization of the registers in this I O
map
In addition the NS486SXF core processor itself requires
several descriptor tables and initialization parameters that
must be set by user-written start-up software
The NS486SXF is designed from the ground up for optimum
price performance in embedded systems This makes the
NS486SXF the logical choice as the base hardware plat-
form for executing an embedded operating system kernel
such as those available from Microtec International Wind
River ISI QNX and many others Any Operating System or
Real-Time Executive that will operate in a segmented or flat
memory model protect mode environment is a suitable com-
plement to the NS486SXF
Also there are many third party tool sets that will allow an
executable application to be built to run directly on the tar-
get hardware without an O S environment
http www national com
8