ad1812 Analog Devices, Inc., ad1812 Datasheet - Page 13

• Manufacturer Part Number: ad1812
• Description: Soundport Controller
• Manufacturer: Analog Devices, Inc.

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SOUND BLASTER EMULATION
Sound Blaster emulation is provided using a combination of the
embedded signal processor and dedicated hardware. All Sound
Blaster Pro version 2.01 functions are supported including
record. The hardware registers are fully implemented within the
AD1812, and the internal signal processor executes a command
controller to interpret all commands. The AD1812 uses the in-
ternal signal processor for decoding compressed files compatible
with Sound Blaster ADPCM.
MUSIC SYNTHESIZER EMULATION
The AD1812 includes an embedded signal processor based on
Analog Devices’ 16-bit fixed-point digital signal processor fam-
ily. All DSP instructions are ROM coded internally. The
music synthesis algorithm running on the signal processor emu-
lates the functions of industry standard OPL3 FM synthesizer
chips and delivers 20 voice polyphony. A dedicated pair of
DACs converts the digitally synthesized music before mixing
with the AD1812 codec line output.
EuSynth-1+ was developed by EuPhonics, a research and prod-
uct development company that specializes in audio processing
and electronic music synthesis.
MPU-401 INTERFACE
The primary interface for communicating MIDI data to and
from the host PC is the emulated MPU-401 interface. The
MPU-401 interface includes has a built-in FIFO for communi-
cating to the host bus.
GAME PORT INTERFACE
An IBM-compatible game port interface is provided on-chip.
The game port is capable of supporting up to two joysticks.
Connecting the game port to a 15-pin D-sub connector requires
only a few capacitors and resistors. The AD1812 includes a
built-in game port timer.
MODEM INTERFACE
Asserting the MODEM_EN pin on the AD1812 provides chip
select, interrupt handling and address decoding for an external
modem chipset. The AD1812 decodes the modem ISA bus
address and issues a modem select on the MODEM_SEL pin.
Interrupts generated by the external modem are handled on the
MODEM_IRQ pin, converted to the assigned system interrupt
by the AD1812, and posted to the ISA bus. The modem inter-
face operates in a PnP or non-PnP enabled system.
PLUG AND PLAY (PnP)
The AD1812 can be used under PnP control or in a non-PnP
mode. The non-PnP registers mimic the PnP register set, ex-
cept for the user defined addresses for the PnP “ADDRESS”
and “WRITE_DATA” registers. The PnP registers are selected
by asserting the PnP pin. With the PnP pin deasserted, the
non-PnP registers are selected.
EuSynth-1+
–13–
Port Name
ADDRESS
WRITE_DATA 0xA79 (Printer Status Port + 0x800)
READ_DATA
Port Name
ADDRESS
WRITE_DATA 0x235
READ_DATA
PnP AD1812 (Card) Status
For cards in PnP mode (PnP_Enable asserted), the Plug and
Play ISA Specification describes how to transfer the AD1812
from its start-up state, “Wait For Key” State, to the configura-
tion state, “Config” State. In the configuration state, the I/O
ranges, interrupt channels, and DMA channels can be assigned.
For non-PnP operation, no initialization protocol is needed
because the card is locked in the configuration state.
Configuration Register Description
The following describes only the subset of PnP Registers that
are unique to the AD1812 or necessary for non-PnP operation.
All other PnP registers are described in the Plug and Play ISA
Specification.
A register is selected by performing an 8-bit I/O write to the
ADDRESS Port, followed by either a read from the READ_DATA
location or a write to the WRITE_DATA location. Successive
reads or writes to a single register can be done without rewriting
the ADDRESS register. The following are valid values for the
ADDRESS Port.
Register Name Value
RD_DATA Port 0x00
Config Control
Logical Device
Number
Powerdown
Table VI. Non-Plug and Play Registers (PNP Deasserted)
Table V. Plug and Play Registers (PNP Asserted)
Table VII. PnP Address Port Registers
Location
0x279 (Printer Status Port)
Relocatable in Range 0x203 – 0x3FF
Location
0x234
Relocatable in Range 0x203 – 0x3FF
0x07
0x20
Address
0x02
Type
Write-Only Sets the value of the
Write-Only Resets all logical devices.
Read/Write Selects current logical
Read/Write Manages power for
Description
READ_DATA Port.
device.
portions of the AD1812.
AD1812
Type
Write-Only
Write-Only
Read-Only
Type
Write-Only
Write-Only
Read-Only