AM29240EH AMD [Advanced Micro Devices], AM29240EH Datasheet - Page 8

• Manufacturer Part Number: AM29240EH
• Description: Enhanced High-Performance RISC Microcontrollers
• Manufacturer: AMD [Advanced Micro Devices]

during fly-by transfers. A higher fly-by DMA transfer can
interrupt a lower fly-by transfer.
Refresh does not pre-empt a fly-by transfer. A DMA
transfer continues until either DREQx is deasserted, the
transfer is interrupted by a higher priority DMA, or the
Count Terminate Enable (CTE) bit is set. No refreshes
will occur until the fly-by transfer is completed, so fly-by
transfers must be less than one refresh interval in
length. The DREQx signal must be configured as level-
sensitive in the DRAM Control Register.
Parity checking and generation cannot be performed
during a fly-by transfer. Note also that zero-wait-state
ROM cannot be used with fly-by DMA.
I/O Port
The I/O port permits direct access to 16 individually pro-
grammable external input/output signals. Eight of these
signals can be configured to cause interrupts.
Parallel Port
The parallel port implements a bidirectional IBM PC-
compatible parallel interface to a host processor.
Serial Port
The serial port implements up to two full-duplex UARTs.
Serializer/Deserializer
The serializer/deserializer (video interface) on the
Am29240EH and Am29245EH microcontrollers permits
direct connection to a number of laser-marking engines,
video displays, or raster input devices such as scanners.
Interrupt Controller
The interrupt controller generates and reports the status
of interrupts caused by on-chip peripherals.
Wide Range of Price/Performance Points
To reduce design costs and time-to-market, the product
designer can use the Am29200 microcontroller family
and one basic system design as the foundation for an
entire product line. From this design, numerous imple-
mentations of the product at various levels of price and
performance may be derived with minimum time, effort,
and cost.
The Am29240EH RISC microcontroller series supports
this capability through various combinations of on-chip
caches, programmable memory widths, programmable
wait states, burst-mode and page-mode access sup-
port, bus compatibility, and 29K family software compat-
ibility. A system can be upgraded using various memory
architectures without hardware and software redesign.
The ROM controller accommodates memories that are
either 8, 16, or 32 bits wide, and the DRAM controller ac-
commodates dynamic memories that are 32 bits wide.
This unique feature provides a flexible interface to low-
cost memory, as well as a convenient, flexible upgrade
8
Am29240 EH Microcontroller Series
P R E L I M I N A R Y
path. For example, a system can start with a 16-bit ROM
memory design and can subsequently improve perfor-
mance by migrating to a 32-bit ROM memory design.
One particular advantage is the ability to add memory in
half-megabyte increments. This provides significant
cost savings for applications that do not require larger
memory upgrades.
The Am29200, Am29202, Am29205, Am29240,
Am29245, and Am29243EH microcontrollers allow us-
ers to address an extremely wide range of cost perfor-
mance points, with higher performance and lower cost
than existing designs based on CISC microprocessors.
Glueless System Interfaces
The Am29240EH microcontroller series also minimizes
system cost by providing a glueless attachment to exter-
nal ROMs, DRAMs, and other peripheral components.
Processor outputs have edge-rate control that allows
them to drive a wide range of load capacitances with low
noise and ringing. This eliminates the cost of external
logic and buffering.
Bus and Software Compatibility
Compatibility within a processor family is critical for
achieving a rational, easy upgrade path. Processors in
the Am29240EH microcontroller series are all members
of a bus-compatible family of RISC microcontrollers. All
members of this family—the Am29205, Am29202,
Am29200, Am29240, Am29245, and Am29243EH mi-
crocontrollers—allow improvements in price, perfor-
mance, and system capabilities without requiring that
users redesign their system hardware or software. Bus
compatibility ensures a convenient upgrade path for fu-
ture systems.
The Am29240EH microcontroller series is available in a
208-pin plastic quad flat-pack (PQFP) package. The
Am29240EH microcontroller series is signal-compatible
with the Am29200 and the Am29205 microcontrollers.
Moreover, the Am29240EH microcontroller series is
binary compatible with existing RISC microcontrollers
and other members of the 29K family (the Am29000,
Am29005, Am29030, Am29035, Am29040, and
Am29050 microprocessors, as well as the Am29200,
Am29202, and Am29205 microcontrollers). The
Am29240EH microcontroller series provides a migra-
tion path to low-cost, high-performance, highly inte-
grated systems from other 29K family members,
without requiring expensive rewrites of application
software.
Debugging and Testing
The Am29240EH microcontroller series provides de-
bugging and testing features at both the software and
hardware levels.