
106
Agere Systems Inc.
T8302 Internet Protocol Telephone
Advanced RISC Machine (
ARM
)
Data Sheet
July 2001
10 Ethernet 10/100 MAC
(continued)
10.7 Register Descriptions
10.7.1 MAC Controller Setup Register
The
MAC controller setup register
is used to set up MAC control bits. The transmit and receive state machines
are reset with the appropriate reset bits. The transmit and receive enable bits must be set for the MAC controller to
send or receive data from the MAC and FIFOs.
Table 78. MAC Controller Setup Register
Address 0xE001 0000
11
SAMUL
PROMM
5
MFDUP
APDCRC
Bit #
Name
Bit #
Name
Bit #
15:14
15:14
13
12
10
9
8
SPEED_SEL
7
DEFER
Name
SPEED_SEL MDC rate of PCLK (system clock). MDC is the management data clock for the PHYs. The
MDC rate must be kept below 6.25 MHz, therefore,
SPEED_SEL
should be programmed
accordingly. For example: if PCLK is 57 MHz,
MDC
= PCLK/8 = 7.125 MHz,
(
SPEED_SEL
= 11) is an invalid setting and
SPEED_SEL
= 00, 01 or 10 should be used.
00
MDC = PCLK/64
01
MDC = PCLK/32
10
MDC = PCLK/16
11
MDC = PCLK/8
SBCSTP
Store broadcast packets.
SBCSTP
6
ISQE
TMODE
3:2
RETRY[1:0]
Description
INVCRC
1:0
PREAMBLE[1:0]
BSEL
—
—
4
13
If 1, all broadcast packets are stored.
If 0, no broadcast packets are stored.
Store all multicast packets.
Indicates that all multicast packets should be stored.
Promiscuous mode.
When 1, this indicates all packets should be received without
address matching.
Reserved for factory testing. This should be programmed to 0.
Invert
CRC
(active-high)
.
Used to invert the polarity of the 32-bit
CRC
polynomial.
The
nor-
mal
CRC
is inverted prior to transmission.
12
11
SAMUL
PROMM
10
9
TMODE
INVCRC
If
INVCRC
is high, the normal
CRC
is reinverted prior to sending, forcing a
CRC
error.
Backoff select (active-low).
Used to control whether the binary backoff algorithm is used
during collision handling.
8
BSEL
If
BSEL
is high, the backoff algorithm is not used. The transmitter jams for 32
TX_CLK
cycles and attempts to retransmit after 96 bit times (normal IFG).
If
BSEL
is low, the transmitter follows the normal binary backoff algorithm following a col-
lision.
Defer (active-high).
Used to force the transmitter to abort a transmission attempt if it has
deferred for more than 24,288
TX_CLK
cycles. Deferring starts when the transmitter is
ready to transmit, but is prevented from doing so because
CRS
is active. Defer time is not
cumulative. If the transmitter defers for 10,000 bit times, then transmits, collides, backs off,
and then has to defer again after completion of backoff, the deferral timer resets to 0 and
restarts.
7
DEFER
If
DEFER
is low, the transmitter defers indefinitely.