ad1816a Analog Devices, Inc., ad1816a Datasheet - Page 42

• Manufacturer Part Number: ad1816a
• Description: Soundport Controller
• Manufacturer: Analog Devices, Inc.

AD1816A
AD1816 AND AD1816A COMPATIBILITY
The AD1816 and AD1816A are pin for pin and functionally compatible. The AD1816A may be dropped directly into an existing
AD1816 design. However, the AD1816A has greater pin assignment flexibility to accommodate a wider range of applications and for
controlling extra logical devices such as a modem chip set or an Enhanced IDE controller. Pin assignments are controlled by the ex-
ternal EEPROM. Consequently, the optional EEPROM must be reprogrammed to configure the AD1816A.
USING AN EEPROM WITH THE AD1816 OR AD1816A
The AD1816 and AD1816A support an optional Plug and Play resource ROM. If present, the ROM must be a two-wire serial de-
vice (e.g. Xicor X24C02) and the clock and data lines should be wired to EE_CLK and EE_DATA pins; pull-up resistors are re-
quired on both signals. The EEPROM’s A2 and A1 pins (also A0 for 256-byte EEPROMs) must all be tied to ground. The write
control pin (WC*) must be tied to power if you wish to program the EEPROM in place; otherwise, we recommend tying it to ground
to prevent accidental writes.
The EEPROM interface logic examines the state of the EE_CLK pin shortly after RESET is deasserted and whenever the Plug and
Play reset register (02h) is written with a value X such that ([X & 1] 0). If an EEPROM is connected, EE_CLK is pulled high and
the EEPROM logic attempts to read the first ROM byte (page 0, byte 0). If EE_CLK is tied low, the internal ROM is used; in this
case EE_DATA is used to set the state of VOL_EN, and should also be tied high or low. EE_CLK is not used as an input at any
other time.
The initial part of the ROM is not part of the Plug and Play resource data. It consists of a number of flags that enable optional func-
tionality. The number of flag bytes and the purpose of each bit depend on whether an AD1816 or an AD1816A is being used.
AD1816 FLAG BYTE
The AD1816 has a single flag byte that is used as shown below:
MODEM_EN
XTRA_EN
XTRA_IRQ
VOL_EN
XTRA_SIZE/
VOL_SEL
The three MSBs in the first byte of the AD1816 EEPROM are used to verify that the EEPROM data is valid. The bits are compared
to the values shown; if a mismatch is found, then the EEPROM will be ignored. The internal ROM will be used to perform PnP
enumeration, and the MODEM and XTRA logical devices will not be available. Hardware volume will be enabled on the I
The SPORT is disabled.
USING THE AD1816 WITHOUT AN EEPROM
If the EEPROM is absent (EE_CLK pin = GND), the flags are set as shown below:
MODEM_EN = XTRA_EN = XTRA_IRQ = VOL_SEL = 0
VOL_EN = EE_DATA pin
7
1
Program to one to enable the modem logical device. This logical device has an I/O range and an IRQ. The I/O
range has the following requirements:
– Length of eight bytes
– Alignment of eight bytes
– 16-bit address decode
Program to zero to enable I
Program to one to enable the XTRA logical device. This logical device has an I/O range, an optional IRQ, and an
optional DMA. The I/O range has the following requirements:
– Length of eight bytes or 16 bytes, selectable by XTRA_SIZE
– Alignment of eight bytes or 16 bytes, matches length
– 16-bit address decode
Program to zero to enable the DSP serial port.
Program to one to include an IRQ in the XTRA logical device. When enabled, the IRQ level and type are pro-
grammed through PnP registers 0x70 and 0x71. (Note: For the 1816, the IRQ type is hard coded and rising edge
triggered.)
Program to one to enable hardware volume control.
The function of this bit depends on XTRA_EN. If XTRA_EN is one, this bit selects the size of the XTRA
device’s I/O range. Program to one to make the XTRA logical device I/O length 16 bytes. Program to zero to set
the XTRA logical device I/O length to eight bytes. The alignment specified in the resource data must be an integer
multiple of the length. If XTRA_EN is zero (and VOL_EN is one), then this bit selects the location of the hard-
ware volume control pins. Program to zero to replace I
place the SPORT.
6
0
5
0
2
S Port 1.
XTRA_SIZE
VOL_SEL
4
–42–
VOL_EN
3
2
S0 with the volume control pins; program to one to re-
XTRA_IRQ
2
XTRA_EN
1
MODEM_EN
0
2
S0 port.
REV. A