AM29240EH AMD [Advanced Micro Devices], AM29240EH Datasheet - Page 7

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

KEY FEATURES AND BENEFITS
The Am29240EH microcontroller series extends the line
of RISC microcontrollers based on 29K family architec-
ture, providing performance upgrades to the Am29205
and Am29200 microcontrollers. The RISC microcontrol-
ler product line allows users to benefit from the very high
performance of the 29K family architecture, while also
capitalizing on the very low system cost made possible
by integrating processor and peripherals.
The Am29240EH microcontroller series expands the
price/performance range of systems that can be built
with the 29K family. The Am29240EH microcontroller
series is fully software compatible with the Am29000,
Am29005, Am29030, Am29035, Am29040, and
Am29050 microprocessors, as well as the Am29200
and Am29205 microcontrollers. It can be used in exist-
ing 29K family microcontroller applications without soft-
ware modifications.
On-Chip Caches
The Am29240EH microcontroller series incorporates a
4-Kbyte, two-way instruction cache that supplies most
processor instructions without wait states at the proces-
sor frequency. For best performance, the instruction
cache supports critical-word-first reloading with fetch-
through, so that the processor receives the required
instruction and the pipeline restarts with minimum delay.
The instruction cache has a valid bit per word to mini-
mize the reload overhead. All cache array elements are
visible to software for testing and preload.
The Am29240EH and Am29243EH microcontrollers in-
corporate a 2-Kbyte, two-way set-associative data
cache. The data cache appears in the execute stage of
the processor pipeline, so that loaded data is available
immediately to the next instruction. This provides the
maximum performance for loads without requiring load
scheduling. This minimizes the time the processor waits
on external data as well as minimizing the reload time.
The data cache uses a write-through policy with a two-
entry write buffer. Byte, half-word, and word reads and
writes are supported. All cache array elements are vis-
ible to software for testing and preload.
Single-Cycle Multiplier
The Am29240EH and Am29243EH microcontrollers
incorporate a full combinatorial multiplier that accepts
two 32-bit input operands and produces a 32-bit result
in a single cycle. The multiplier can produce a 64-bit re-
sult in two cycles. The multiplier permits maximum per-
formance without requiring instruction scheduling,
since the latency of the multiply is the same as the la-
tency of other integer operations. High-performance
multiplication benefits imaging, signal processing, and
state modeling applications.
Am29240 EH Microcontroller Series
P R E L I M I N A R Y
Complete Set of Common Peripherals
The Am29240EH microcontroller series minimizes sys-
tem cost by incorporating a complete set of system facili-
ties commonly found in embedded applications,
eliminating the cost of additional components. The on-
chip functions include: a ROM controller, a DRAM con-
troller, a peripheral interface adapter, a DMA controller,
a programmable I/O port, a parallel port, up to two serial
ports, and an interrupt controller. A video interface is
also included in the Am29240EH and Am29245EH mi-
crocontrollers for printer, scanner, and other imaging ap-
plications. These facilities allow many simple systems to
be built using only the Am29240EH microcontroller se-
ries, external ROM, and/or DRAM memory.
ROM Controller
The ROM controller supports four individual banks of
ROM or other static memory, each with its own timing
characteristics. Each ROM bank may be a different size
and may be either 8, 16, or 32 bits wide. The ROM banks
can appear as a contiguous memory area of up to 64
Mbytes in size. The ROM controller also supports byte,
half-word, and word writes to the ROM memory space
for devices such as flash EPROMs and SRAMs.
DRAM Controller
The DRAM controller supports four separate banks of
dynamic memory. Each bank may be a different size and
must be 32 bits wide. The DRAM banks can appear as a
contiguous memory area of up to 64 Mbytes in size. The
DRAM controller supports two- or three-cycle accesses
(programmable by software), with single-cycle page-
mode and burst-mode accesses. Burst accesses are
supported at two initial, one burst, or three initial, one
burst.
Peripheral Interface Adapter
The Peripheral Interface Adapter (PIA) permits glueless
interfacing to as many as six external peripheral chips.
The PIA allows for additional system features imple-
mented by external peripheral chips.
DMA Controller
The DMA controller provides up to four channels for
transferring data between the DRAM and internal or ex-
ternal peripherals.
Fly-by DMA transfers data directly between an external
peripheral and DRAM or ROM, permitting very high data
bandwidth. The peripheral must support the timing of
the memory (DRAM or ROM). The transfer occurs at the
rate of one 32-bit word per cycle, if DRAM page-mode
accesses or ROM burst-mode or single-cycle accesses
are enabled.
For page-mode DRAM, the TDMA signal is asserted on
the rising edge following the last access. For an initial
access, TDMA is asserted simultaneously with DACKx.
DMA wait states and peripheral wait states are ignored
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