
104
Agere Systems Inc.
T8302 Internet Protocol Telephone
Advanced RISC Machine (
ARM
)
Data Sheet
July 2001
10 Ethernet 10/100 MAC
(continued)
10.5 MAC Controller, Registers, and Counters
There are several registers and counters in the MAC controller. The registers include
control setup registers
,
control registers
, and
status registers
. There are thirty-two 48-bit address matching registers that are used to
determine whether received multicast packets are stored. Location 0 in the
address match memory registers
is
always reserved for the MAC’s physical address. The remaining registers are used to store multicast addresses
that are compared against received packet destination addresses. If there is a match, the packet is stored.
If store-all multicast packets mode is selected (
SAMUL
set to 1 in the
MAC controller setup register
;
see Table
78 on page 106
) all multicast packets will be stored without regard to values in the
address match registers
. If
promiscuous mode is selected (
PROMM
set to 1 in the
MAC controller setup register
), all packets are stored (no
address matching is performed).
The counters are used to control the MDIO interface to the PHYs, assemble and send pause control frames, and
recognize VLAN packets.
10.6 Control Frame Operation
The MAC supports control frame transmission and automatic pause control frame response for use in flow-control
of full-duplex networks. In the transmit direction, the MAC can transmit control frames to the far end without having
to go through the process of writing to the transmit FIFO. This is done by programming register addresses
0XE001 000C to 0XE001 002C with the control frame information and then setting the
CNTLXMIT
bit (in the
MAC
controller transmit control register
) to initiate transmission.
In the receive direction, the MAC will respond to the reception of pause commands by pausing the MAC transmitter
for the requested number of bit times. To enable this automatic pause response, register addresses
0XE001 000C to 0XE001 0028 must be programmed with the proper values for a pause command.
See
Table 81
—
Table 85
for more information.