Am79C972
115
mode and the Am79C972 con-
troller receives a Magic Packet
frame. When MPINT is set to 1,
INTA is asserted if IENA (CSR0,
bit 6) and the enable bit MPINTE
are set to 1.
Read/Write accessible always.
MPINT is cleared by the host by
writing a 1. Writing a 0 has no af-
fect. MPINT is cleared by
H_RESET, S_RESET, or by set-
ting the STOP bit.
3
MPINTE
Magic Packet Interrupt Enable. If
MPINTE is set to 1, the MPINT bit
will be able to set the INTR bit.
Read/Write accessible always.
MPINT is cleared to 0 by
H_RESET or S_RESET and is
not affected by setting the STOP
bit.
2
MPEN
Magic Packet Enable. MPEN al-
lows activation of the Magic
Packet mode by the host. The
Am79C972 controller will enter
the Magic Packet mode when
both MPEN and MPMODE are
set to 1.
Read/Write accessible always.
MPEN is cleared to 0 by
H_RESET or S_RESET and is
not affected by setting the STOP
bit.
1
MPMODE
The Am79C972 controller will en-
ter the Magic Packet mode when
MPMODE is set to 1 and either
PG is asserted or MPEN is set to
1.
Read/Write accessible always.
MPMODE is cleared to 0 by
H_RESET or S_RESET and is
not affected by setting the STOP
bit
0
SPND
Suspend. Setting SPND to 1 will
cause the Am79C972 controller
to start requesting entrance into
suspend mode. The host must
poll SPND until it reads back 1 to
determine that the Am79C972
controller has entered the sus-
pend mode. Setting SPND to 0
will get the Am79C972 controller
out of suspend mode. SPND can
only be set to 1 if STOP (CSR0,
bit 2) is set to 0. H_RESET,
S_RESET or setting the STOP bit
will get the Am79C972 controller
out of suspend mode.
Requesting entrance into the
suspend mode by the host de-
pends on the setting of the
FASTSPNDE bit (CSR7, bit 15).
Refer to the bit description of the
FASTSPNDE bit and the Sus-
pend section in
Detailed Func-
tions, Buffer Management Unit
for details.
In suspend mode, all of the CSR
and BCR registers are accessi-
ble. As long as the Am79C972
controller is not reset while in
suspend mode (by H_RESET,
S_RESET or by setting the STOP
bit), no re-initialization of the de-
vice is required after the device
comes out of suspend mode. The
Am79C972 controller will contin-
ue at the transmit and receive de-
scriptor ring locations, from
where it had left, when it entered
the suspend mode.
Read/Write accessible always.
SPND is cleared by H_RESET,
S_RESET, or by setting the
STOP bit.
CSR6: RX/TX Descriptor Table Length
Bit
Name
Description
31-16
RES
Reserved locations. Written as
zeros and read as undefined.
15-12
TLEN
Contains a copy of the transmit
encoded ring length (TLEN) field
read from the initialization block
during the Am79C972 controller
initialization. This field is written
during the Am79C972 controller
initialization routine.
Read accessible only when either
the STOP or the SPND bit is set.
Write operations have no effect
and should not be performed.
TLEN is only defined after initial-
ization. These bits are unaffected