ADSP-21060 Analog Devices, ADSP-21060 Datasheet - Page 4

• Manufacturer Part Number: ADSP-21060
• Description: ADSP-2106x SHARC DSP Microcomputer Family
• Manufacturer: Analog Devices

Instruction Cache
The ADSP-2106x includes an on-chip instruction cache that
enables three-bus operation for fetching an instruction and two
data values. The cache is selective—only the instructions whose
fetches conflict with PM bus data accesses are cached. This
allows full-speed execution of core, looped operations such as
digital filter multiply-accumulates and FFT butterfly processing.
Data Address Generators with Hardware Circular Buffers
The ADSP-2106x’s two data address generators (DAGs) imple-
ment circular data buffers in hardware. Circular buffers allow
efficient programming of delay lines and other data structures
required in digital signal processing, and are commonly used in
digital filters and Fourier transforms. The two DAGs of the
ADSP-2106x contain sufficient registers to allow the creation of
up to 32 circular buffers (16 primary register sets, 16 second-
ary). The DAGs automatically handle address pointer wrap-
around, reducing overhead, increasing performance, and
simplifying implementation. Circular buffers can start and end
at any memory location.
Flexible Instruction Set
The 48-bit instruction word accommodates a variety of parallel
operations, for concise programming. For example, the ADSP-
2106x can conditionally execute a multiply, an add, a subtract
and a branch, all in a single instruction.
ADSP-21060/ADSP-21060L FEATURES
Augmenting the ADSP-21000 family core, the ADSP-21060
adds the following architectural features:
Dual-Ported On-Chip Memory
The ADSP-21060 contains four megabits of on-chip SRAM,
organized as two blocks of 2 Mbits each, which can be config-
ured for different combinations of code and data storage.
Each memory block is dual-ported for single-cycle, independent
accesses by the core processor and I/O processor or DMA con-
troller. The dual-ported memory and separate on-chip buses
allow two data transfers from the core and one from I/O, all in a
single cycle.
On the ADSP-21060, the memory can be configured as a maxi-
mum of 128K words of 32-bit data, 256K words of 16-bit data,
80K words of 48-bit instructions (or 40-bit data), or combina-
tions of different word sizes up to four megabits. All of the
memory can be accessed as 16-bit, 32-bit, or 48-bit words.
A 16-bit floating-point storage format is supported that effec-
tively doubles the amount of data that may be stored on-chip.
Conversion between the 32-bit floating-point and 16-bit floating-
point formats is done in a single instruction.
While each memory block can store combinations of code and
data, accesses are most efficient when one block stores data,
using the DM bus for transfers, and the other block stores
instructions and data, using the PM bus for transfers. Using the
DM bus and PM bus in this way, with one dedicated to each
memory block, assures single-cycle execution with two data
transfers. In this case, the instruction must be available in the
cache. Single-cycle execution is also maintained when one of the
data operands is transferred to or from off-chip, via the ADSP-
2106x’s external port.
ADSP-21060/ADSP-21060L
Off-Chip Memory and Peripherals Interface
The ADSP-2106x’s external port provides the processor’s inter-
face to off-chip memory and peripherals. The 4-gigaword off-
chip address space is included in the ADSP-2106x’s unified
address space. The separate on-chip buses—for PM addresses,
PM data, DM addresses, DM data, I/O addresses, and I/O
data—are multiplexed at the external port to create an external
system bus with a single 32-bit address bus and a single 48-bit
(or 32-bit) data bus.
Addressing of external memory devices is facilitated by on-chip
decoding of high-order address lines to generate memory bank
select signals. Separate control lines are also generated for sim-
plified addressing of page-mode DRAM. The ADSP-2106x
provides programmable memory wait states and external
memory acknowledge controls to allow interfacing to DRAM
and peripherals with variable access, hold, and disable time
requirements.
Host Processor Interface
The ADSP-2106x’s host interface allows easy connection to
standard microprocessor buses, both 16-bit and 32-bit, with
little additional hardware required. Asynchronous transfers at
speeds up to the full clock rate of the processor are supported.
The host interface is accessed through the ADSP-2106x’s exter-
nal port and is memory-mapped into the unified address space.
Four channels of DMA are available for the host interface; code
and data transfers are accomplished with low software overhead.
The host processor requests the ADSP-2106x’s external bus
with the host bus request (HBR), host bus grant (HBG), and
ready (REDY) signals. The host can directly read and write the
internal memory of the ADSP-2106x, and can access the DMA
channel setup and mailbox registers. Vector interrupt support is
provided for efficient execution of host commands.
DMA Controller
The ADSP-2106x’s on-chip DMA controller allows zero-
overhead data transfers without processor intervention. The
DMA controller operates independently and invisibly to the
processor core, allowing DMA operations to occur while the
core is simultaneously executing its program instructions.
DMA transfers can occur between the ADSP-2106x’s internal
memory and either external memory, external peripherals or a
host processor. DMA transfers can also occur between the
ADSP-2106x’s internal memory and its serial ports or link
ports. DMA transfers between external memory and external
peripheral devices are another option. External bus packing to
16-, 32-, or 48-bit words is performed during DMA transfers.
Ten channels of DMA are available on the ADSP-2106x—two
via the link ports, four via the serial ports, and four via the
processor’s external port (for either host processor, other
ADSP-2106xs, memory or I/O transfers). Four additional link
port DMA channels are shared with serial port 1 and the exter-
nal port. Programs can be downloaded to the ADSP-2106x
using DMA transfers. Asynchronous off-chip peripherals can
control two DMA channels using DMA Request/Grant lines
(DMAR1-2, DMAG1-2 ). Other DMA features include inter-
rupt generation upon completion of DMA transfers and DMA
chaining for automatic linked DMA transfers.