Motorola MPC8260 - Manual (Page 678)

24-10 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
24.8 Programming the Ethernet Controller
The core conÞgures the SCC to operate as an Ethernet controller by setting GSMR[MODE]
to 0b1100. Receive and transmit errors are reported through RxBD and TxBD. Several
GSMR Þelds must be programmed to special values for Ethernet. Set DSR[SYN1] to 0x55
and DSR[SYN2] to 0xDE. The 6 bytes of preamble programmed in the GSMR, in
combination with the DSR programming, causes 8 bytes of preamble on transmit
(including the 1-byte start delimiter with the value 0xD5).
24.9 SCC Ethernet Commands
Transmit and receive commands are issued to the CP command register (CPCR).
Table 24-2 describes transmit commands.
0x9E TADDR_H Hword Allows addition and deletion of addresses from individual and group hash tables.
After placing an address in TADDR, issue a SET GROUP ADDRESS command.
TADDR_L (temp address low) is the least-signiÞcant half word and TADDR_H
(temp address high) is the most-signiÞcant half word.
0x A0 TADDR_M
0x A2 TADDR_L
1 From SCC base address. See Section 19.3.1, ÒSCC Base Addresses.Ó
Table 24-2. Transmit Commands
Command Description
STOP
TRANSMIT
When used with the Ethernet controller, this command violates a speciÞc behavior of an Ethernet/IEEE
802.3 station. It should not be used.
GRACEFUL
STOP
TRANSMIT
Used to ensure that transmission stops smoothly after the current frame Þnishes or has a collision.
SCCE[GRA] is set once transmission stops, at which point Ethernet transmit parameters and their BDs
can be updated. TBPTR points to the next TxBD. Transmission begins once the R bit of the next BD is
set and a
RESTART TRANSMIT command is issued.
Note that if GRACEFUL STOP TRANSMIT is issued and the current frame ends in a collision, TBPTR points
to the start of the collided frame with the R bit still set in the BD. The frame looks as if it was never sent.
RESTART
TRANSMIT
Enables transmission of characters on the transmit channel. The Ethernet controller expects it after a
GRACEFUL STOP TRANSMIT command is issued or a transmitter error. The Ethernet controller resumes
transmission from the current TBPTR in the channel TxBD table.
INIT TX
PARAMETERS
Initializes transmit parameters in this serial channel parameter RAM to reset state. Issue only when the
transmitter is disabled.
INIT TX and RX PARAMETERS resets both transmit and receive parameters.
Table 24-1. SCC Ethernet Parameter RAM Memory Map (Continued)
Offset 1 Name Width Description