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ThunderBird Avenger
TM
PCI Audio SAA7785
Accelerator
Philips Semiconductors Preliminary Specification
1999 Nov 12 64
TABLE 67 MIN_GNT Register - MINGNT (RO)
TABLE 68 MAX_LAT Register - MAXLAT (RO)
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.
Bit Name R/W Function
7:0 INTPIN RO 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.
PCI CFG 2D7D6D5D4D3D2D1D0
Offset 3Eh
MINGNT[7:0]
POR Value
00000000
Bit Name R/W Function
7:0 MINGNT RO 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.
PCI CFG 2D7D6D5D4D3D2D1D0
Offset 3Fh
MAXLAT[7:0]
POR Value
00000000
Bit Name R/W Function
7:0 MAXLAT RO 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.