
88
Am79C978
Figure 46.
OnNow Functional Diagram
Link Change Detect
Link change detect is one of wake-up events defined
by the OnNow specification. Link Change Detect mode
is set when the LCMODE bit (CSR116, bit 8) is set ei-
ther by software or loaded through the EEPROM.
When this bit is set, any change in the Link status will
cause the LCDET bit (CSR116, bit 9) to be set. When
the LCDET bit is set, the PME_STATUS bit (PMCSR
register, bit 15) will be set. If either the PME_EN bit
(PMCSR, bit 8) or the PME_EN_OVR bit (CSR116, bit
10) are set, then the PME will also be asserted.
OnNow Pattern Match Mode
In the OnNow Pattern Match Mode, the Am79C978 de-
vice compares the incoming packets with up to eight
patterns stored in the Pattern Match RAM (PMR). The
stored patterns can be compared with part or all of in-
coming packets, depending on the pattern length and
the way the PMR is programmed. When a pattern
match has been detected, then PMAT bit (CSR116, bit
7) is set. The setting of the PMAT bit causes the
PME_STATUS bit (PMCSR, bit 15) to be set, which in
turn will assert the PME pin if the PME_EN bit
(PMCSR, bit 8) is set.
Pattern Match RAM (PMR)
PMR is organized as an array of 64 words by 40 bits as
shown in Figure 47. The PMR is programmed indirectly
through BCRs 45, 46, and 47. When BCR45 is written
and the PMAT_MODE bit (BCR45, bit 7) is set to 1,
Pattern Match logic is enabled. No bus accesses into
the PMR are possible when the PMAT_MODE bit is
set, and BCR46, BCR47, and all other bits in BCR45
are ignored. When PMAT_MODE is set, a read of
BCR45 returns all bits undefined except for
MPDETECT
MPPEN
PG
MPMODE
MPEN
Magic Packet
Link Change
LCMODE
Link Change
MPMAT
LCDET
S
R
Q
Q
DET
CLR
BCR47
BCR46
BCR45
S
R
Q
Q
SET
CLR
S
R
Q
Q
SET
CLR
S
R
Q
Q
SET
CLR
PMAT
Pattern Match
Input
Pattern
PME_STATUS
Pattern Match RAM (PMR)
PME Status
PME_EN
MPMAT
PME_EN_OVR
LCEVENT
PME
S
R
Q
Q
SET
CLR
POR
POR
H_RESET
POR
POR
22206B-50