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4.0 Register Set
(Continued)
DP83816
4.2.14 CLKRUN Control/Status Register
This register mirrors the read/write control of the PMESTS and PMEEN from the PCI Configuration register PMCSR and
controls whether the chip is in the CLKRUNN or PMEN mode.
Bit
Bit Name
Description
5-1
DRTH
Rx Drain Threshold
Specifies the drain threshold in units of 8 bytes. When the number of bytes in the receive FIFO reaches
this value (times 8), or the FIFO contains a complete packet, the receive bus master state machine will
begin the transfer of data from the FIFO to host memory. Care must be taken when setting DRTH to a
value lower than the number of bytes needed to determine if packet should be accepted or rejected. In
this case, the packet might be rejected after the bus master operation to begin transferring the packet
into memory has begun. When this occurs, neither the OK bit or any error status bit in the descriptor’s
cmdsts will be set. A value of 0 is illegal, and the results are undefined.
This value is also used to compare with the accumulated packet length for early receive indication. When
the accumulated packet length meets or exceeds the DRTH value, the RXEARLY interrupt condition is
generated.
0
Reserved
Tag:
CCSR
Size:
32 bits
Hard Reset:
00000000h
Offset:
003Ch
Access:
Read Write
Soft Reset:
unchanged
Bit
Bit Name
Description
31-16
reserved
(reads return 0)
15
PMESTS
PME Status
Sticky bit which represents the state of the PME/CLKRUN logic, regardless of the state of the PMEEN bit.
Mirrored from PCI configuration register PMCSR. Writing a 1 to this bit clears it.
14-9
reserved
(reads return 0)
8
PMEEN
PME Enable
When set to 1, this bit enables the assertion of the PMEN/CLKRUNN pin. When 0, the PMEN/CLKRUNN
pin is forced to be inactive. This value can be loaded from the EEPROM. Mirrored from PCI configuration
register PMCSR.
7-1
unused
(reads return 0)
0
CLKRUN_EN
Clkrun Enable
When set to 1, this bit enables the CLKRUNN functionality of the PMEN/CLKRUNN pin. When 0, normal
PMEN functionality is active.
Summary of Contents for MacPHYTER-II DP83816
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