SAA7785 Datasheet, PDF (64/68 Pages) NXP Semiconductors – ThunderBird Avenger PCI Audio Accelerator

Philips Semiconductors
ThunderBird Avenger^TM PCI Audio
Accelerator
Preliminary Specification
SAA7785
Bit
7:0
Name
INTPIN
R/W
RO
Function
Interrupt Pin. The interrupt pin register tells which interrupt the SSA7785
ThunderBird Avenger™ device uses. The read only value of 00h implies that
the SSA7785 ThunderBird Avenger™ device shares the INT A interrupt pin
with function 0. There is no legacy interrupt support for function 2.
TABLE 67 MIN_GNT Register - MINGNT (RO)
PCI CFG 2
D7
D6
D5
D4
D3
D2
D1
D0
Offset 3Eh
MINGNT[7:0]
POR Value
0
0
0
0
0
0
0
0
Bit
7:0
Name
MINGNT
R/W
RO
Function
Minimum grant specifies how long of a burst period the device needs assum-
ing a clock speed of 33MHz. Since the SSA7785 ThunderBird Avenger™,
function 2, is a target only, this register is read only and set to zero.
TABLE 68 MAX_LAT Register - MAXLAT (RO)
PCI CFG 2
D7
D6
D5
D4
D3
D2
D1
D0
Offset 3Fh
MAXLAT[7:0]
POR Value
0
0
0
0
0
0
0
0
Bit
7:0
Name
MAXLAT
R/W
RO
Function
Maximum latency specifies how often a device needs to gain access to the
PCI bus. The SSA7785 ThunderBird Avenger™, function 2, is a target only,
this register is read only and set to zero.
MULTIMEDIA TIMER
OVERVIEW
The Multimedia Timer is a 20 bit counter with 840ns resolution for general purpose use under host software control. The
timer subsystem consists of the 20-bit counter and I/O space registers. It takes three I/O cycles to read the complete
value of the Timer since the device allows only byte accesses.
The Multimedia Timer will get its time base by dividing down the CCLK clock. An interrupt and flag is provided to deter-
mine if the timer count has rolled over. The timer can either start from zero or be preloaded with a start value.
1999 Nov 12
64