system may insert into an
Am79C978 controller master
transfer. If this value of bus laten-
cy is exceeded, then a MERR will
be indicated in CSR0, bit 11, and
an interrupt may be generated,
depending upon the setting of the
MERRM bit (CSR3, bit 11) and
the IENA bit (CSR0, bit 6).
The value in this register is inter-
preted as the unsigned number of
bus clock periods divided by two,
(i.e., the value in this register is
given in 0.1 ms increments). For
example, the value 0600h (1536
decimal) will cause a MERR to be
indicated after 153.6 ms of bus
latency. A value of 0 will allow an
infinitely long bus latency, i.e.,
bus timeout error will never oc-
cur.
These bits are read/write acces-
sible only when either the STOP
or the SPND bit is set. This regis-
ter is set to 0600h by H_RESET
or S_RESET and is unaffected by
STOP.
CSR112: Missed Frame Count
Bit
Name
Description
Reserved locations. Written as
zeros and read as undefined.
Missed Frame Count. Indicates
the number of missed frames.
MFC will roll over to a count of 0
from the value 65535. The MFCO
bit of CSR4 (bit 8) will be set each
time that this occurs.
Read accessible always. MFC is
read only, write operations are ig-
nored. MFC is cleared by
H_RESET, or S_RESET or by
setting the STOP bit.
CSR114: Receive Collision Count
Bit
Name
Description
Reserved locations. Written as
zeros and read as undefined.
Receive Collision Count. Indi-
cates the total number of colli-
9
LCDET
sions encountered by the
receiver since the last reset of the
counter.
RCC will roll over to a count of 0
from the value 65535. The
RCVCCO bit of CSR4 (bit 5) will
be set each time that this occurs.
These bits are read accessible al-
ways. RCC is read only, write op-
erations are ignored. RCC is
cleared
by
H_RESET
or
S_RESET, or by setting the
STOP bit.
CSR116: OnNow Power Mode Register
Note:
Bits 15-0 in this register are programmable
through the EEPROM.
Bit
Name
Description
Reserved locations. Written as
zeros and read as undefined.
31-16 RES
10 PME_EN_OVR PME_EN Overwrite. When this
bit is set and the MPMAT or
LCDET bit is set, the PME pin will
always be asserted regardless of
the state of the PME_EN bit.
These bits are read/write accessi-
ble only when either the STOP bit
or the SPND bit is set. Cleared by
H_RESET and is not affected by
S_RESET or setting the STOP
bit.
Link Change Detected. This bit is
set when the MII auto-polling log-
ic detects a change in link status
and the LCMODE bit is set.
LCDET is cleared when power is
initially applied (POR).
This bit is always read/write ac-
cessible.
8
LCMODE
Link Change Wake-up Mode.
When this bit is set to 1, the
LCDET bit gets set when the MII
auto polling logic detects a Link
Change.
Read/Write accessible only when
either the STOP bit or the SPND
bit is set. Cleared by H_RESET
and is not affected by S_RESET
or setting the STOP bit.
31-16 RES
15-0
MFC
31-16 RES
15-0
RCC
142
Am79C978
AMD [ ADVANCED MICRO DEVICES ]
