adsp2185 Analog Devices, Inc., adsp2185 Datasheet - Page 3

• Manufacturer Part Number: adsp2185
• Description: Dsp Microcomputer
• Manufacturer: Analog Devices, Inc.

The internal result (R) bus connects the computational units so
the output of any unit may be the input of any unit on the next
cycle.
A powerful program sequencer and two dedicated data address
generators ensure efficient delivery of operands to these compu-
tational units. The sequencer supports conditional jumps, sub-
routine calls and returns in a single cycle. With internal loop
counters and loop stacks, the ADSP-2185 executes looped code
with zero overhead; no explicit jump instructions are required to
maintain loops.
Two data address generators (DAGs) provide addresses for
simultaneous dual operand fetches from data memory and pro-
gram memory. Each DAG maintains and updates four address
pointers. Whenever the pointer is used to access data (indirect
addressing), it is post-modified by the value of one of four pos-
sible modify registers. A length value may be associated with
each pointer to implement automatic modulo addressing for
circular buffers.
Efficient data transfer is achieved with the use of five internal
buses:
• Program Memory Address (PMA) Bus
• Program Memory Data (PMD) Bus
• Data Memory Address (DMA) Bus
• Data Memory Data (DMD) Bus
• Result (R) Bus
The two address buses (PMA and DMA) share a single external
address bus, allowing memory to be expanded off-chip, and the
two data buses (PMD and DMD) share a single external data
bus. Byte memory space and I/O memory space also share the
external buses.
Program memory can store both instructions and data, permit-
ting the ADSP-2185 to fetch two operands in a single cycle, one
from program memory and one from data memory. The ADSP-
2185 can fetch an operand from program memory and the next
instruction in the same cycle.
When configured in host mode, the ADSP-2185 has a 16-bit
Internal DMA port (IDMA port) for connection to external
systems. The IDMA port is made up of 16 data/address pins
and five control pins. The IDMA port provides transparent,
direct access to the DSPs on-chip program and data RAM.
An interface to low cost byte-wide memory is provided by the
Byte DMA port (BDMA port). The BDMA port is bidirectional
and can directly address up to four megabytes of external RAM
or ROM for off-chip storage of program overlays or data tables.
The byte memory and I/O memory space interface supports
slow memories and I/O memory-mapped peripherals with
programmable wait state generation. External devices can
gain control of external buses with bus request/grant signals
(BR, BGH and BG). One execution mode (Go Mode) allows
the ADSP-2185 to continue running from on-chip memory.
Normal execution mode requires the processor to halt while
buses are granted.
The ADSP-2185 can respond to eleven interrupts. There can be
up to six external interrupts (one edge-sensitive, two level-sensitive
and three configurable) and seven internal interrupts generated
by the timer, the serial ports (SPORTs), the Byte DMA port
and the power-down circuitry. There is also a master RESET
signal. The two serial ports provide a complete synchronous
serial interface with optional companding in hardware and a
REV. 0
–3–
wide variety of framed or frameless data transmit and receive
modes of operation.
Each port can generate an internal programmable serial clock or
accept an external serial clock.
The ADSP-2185 provides up to 13 general-purpose flag pins.
The data input and output pins on SPORT1 can be alternatively
configured as an input flag and an output flag. In addition,
eight flags are programmable as inputs or outputs, and three
flags are always outputs.
A programmable interval timer generates periodic interrupts. A
16-bit count register (TCOUNT) decrements every n processor
cycle, where n is a scaling value stored in an 8-bit register
(TSCALE). When the value of the count register reaches zero,
an interrupt is generated and the count register is reloaded from
a 16-bit period register (TPERIOD).
Serial Ports
The ADSP-2185 incorporates two complete synchronous serial
ports (SPORT0 and SPORT1) for serial communications and
multiprocessor communication.
Here is a brief list of the capabilities of the ADSP-2185 SPORTs.
For additional information on Serial Ports, refer to the ADSP-
2100 Family User’s Manual.
• SPORTs are bidirectional and have a separate, double-buff-
• SPORTs can use an external serial clock or generate their own
• SPORTs have independent framing for the receive and trans-
• SPORTs support serial data word lengths from 3 to 16 bits
• SPORT receive and transmit sections can generate unique
• SPORTs can receive and transmit an entire circular buffer of
• SPORT0 has a multichannel interface to selectively receive
• SPORT1 can be configured to have two external interrupts
PIN DESCRIPTIONS
The ADSP-2185 will be available in a 100-lead TQFP package.
In order to maintain maximum functionality and reduce pack-
age size and pin count, some serial port, programmable flag,
interrupt and external bus pins have dual, multiplexed function-
ality. The external bus pins are configured during RESET only,
while serial port pins are software configurable during program
execution. Flag and interrupt functionality is retained concur-
rently on multiplexed pins. In cases where pin functionality is
reconfigurable, the default state is shown in plain text; alternate
functionality is shown in italics.
ered transmit and receive section.
serial clock internally.
mit sections. Sections run in a frameless mode or with frame
synchronization signals internally or externally generated.
Frame sync signals are active high or inverted, with either of
two pulse widths and timings.
and provide optional A-law and -law companding according
to CCITT recommendation G.711.
interrupts on completing a data word transfer.
data with only one overhead cycle per data word. An interrupt
is generated after a data buffer transfer.
and transmit a 24 or 32 word, time-division multiplexed,
serial bitstream.
(IRQ0 and IRQ1) and the Flag In and Flag Out signals. The
internally generated serial clock may still be used in this con-
figuration.
ADSP-2185