Serial Communication Controllers (SCCs)
7-250
MC68360 USER’S MANUAL
MOTOROLA
IADDR1–4. These four registers are used in the hash table function of the individual
addressing mode. The user may write zeros to these values after reset and before the Ether-
net channel is enabled to disable all individual hash address recognition functions. The SET
GROUP ADDRESS command is used to enable the hash table.
TADDR. This parameter allows the user to add and delete addresses from the individual and
group hash tables. After placing an address in TADDR, the user would then issue the SET
GROUP ADDRESS command. TADDR_L is the lowest order word, and TADDR_H is the
highest order word.
7.10.23.9 ETHERNET PROGRAMMING MODEL.
The host configures SCC to operate as
an Ethernet controller by the MODE bits in the GSMR.
The receive errors (collision, overrun, nonoctet aligned frame, short frame, frame too long,
and CRC error) are reported through the Rx BD. The transmit errors (underrun, heartbeat,
late collision, retransmission limit, and carrier sense lost) are reported through the Tx BD.
Several bit fields in the GSMR must be programmed to special values for Ethernet. See the
GSMR for more details. The user should program the DSR as shown below. The 6 bytes of
preamble programmed in the GSMR, in combination with the programming of the DSR
shown below, causes 8 bytes of preamble on transmit (including the 1-byte start delimiter
with the value $D5).
7.10.23.10 ETHERNET COMMAND SET.
Ethernet:Ethernet Command SetThe following
transmit and receive commands are issued to the CR.
NOTE
Before issuing the CP RESET command, configure the TENA
(RTS) pin to be an input. See step 3 of 7.10.23.23 SCC Ethernet
Example. for more information.
7.10.23.10.1 Transmit Commands.
The following paragraphs describe the Ethernet trans-
mit commands.
STOP TRANSMIT Command
.
When used with the Ethernet controller, this command vio-
lates specified behavior of an Ethernet/IEEE 802.3 station. It should not be used.
GRACEFUL STOP TRANSMIT Command
.
The channel GRACEFUL STOP TRANSMIT
command is used to stop transmission in an orderly way. It stops transmission after the cur-
rent frame has completed transmission or undergoes a collision (immediately if there is no
frame being transmitted). The GRA bit in the SCCE will be set once transmission has
stopped. After transmission ceases, the Ethernet transmit parameters, including BDs, may
be modified by the user. The TBPTR will point to the next Tx BD in the table. Transmission
will begin once the R-bit of the next BD is set and the RESTART TRANSMIT command is
issued.
15
14
13
12
SYN2 = $D5
11
10
9
8
7
6
5
4
SYN1 = $55
3
2
1
0