
Am79C978A
89
Figure 48.
Pattern Match RAM
When the controller detects a Magic Packet frame, it sets
the MPMAT bit (CSR116, bit 5), the MPINT bit (CSR5, bit
4), and the PME_STATUS bit (PMCSR, bit 15). If the
PME_EN or the PME_EN_OVR bits are set, the PME will
be asserted as well. If IENA (CSR0, bit 6) and MPINTE
(CSR5, bit 3) are set to 1, INTA will be asserted. Any one
of the four LED pins can be programmed to indicate that
a Magic Packet frame has been received. MPSE (BCR4-
7, bit 9) must be set to 1 to enable that function.
CAUTION:
The polarity of the LED pin can be pro-
grammed to be active HIGH by setting LEDPOL
(BCR4-7, bit 14) to 1.
Once a Magic Packet frame is detected, the con-
troller will discard the frame internally, but will not
resume normal transmit and receive operations
until PG is asserted or MPEN is cleared. Once
both of these events has occurred, indicating that
the system has detected the Magic Packet and is
awake, the controller will continue polling receive
and transmit descriptor rings where it left off. It is
not necessary to re-initialize the device. If the part
is re-initialized, then the descriptor locations will
be reset and the controller will not start where it
left off.
If magic packet mode is disabled by the assertion of PG,
then in order to immediately re-enable Magic Packet
mode, the PG pin must remain deasserted for at least 200
ns before it is reasserted. If Magic Packet mode is dis-
abled by clearing MPEN bit, then it may be immediately
re-enabled by setting MPEN back to 1.
BCR 47
BCR 46
BCR 45
BCR Bit Number 15 8 7 0 15 8 7 0 15 8
PMR_B4
PMR_B3
PMR_B2
PMR_B1
PMR_B0
Pattern Match
RAM Address
Pattern Match RAM Bit Number
39 32 31 24 23 16 15 8 7 0
Comments
0
P3 pointer
P2 pointer
P1 pointer
P0 pointer
Pattern Enable
bits
First Address
1
P7 pointer
P6 pointer
P5 pointer
P4 pointer
X
Second
Address
2
Data Byte 3
Data Byte 2
Data Byte1
Data Byte 0
Pattern Control
Start Pattern
P
1
2+n
Data Byte 4n+3
Date Byte 4n+2
Data Byte 4n+1
Data Byte 4n+0
Pattern Control
End Pattern P
1
J
Data Byte 3
Data Byte 2
Data Byte 1
Data Byte 0
Pattern Control
Start Pattern
P
k
J+m
Data Byte 4m+3 Data Byte 4m+2 Data Byte 4m+1 Data Byte 4m+0
Pattern Control
End Pattern P
k
63
Last Address
7 6 5 4 3 2 1 0
EOP SKIP MASK
22399A-51