Freescale Semiconductor PowerQUICC MPC885 Reference Manual page 766

SCC Ethernet Mode
Table 27-2. SCC Ethernet Parameter RAM Memory Map (continued)
1
Offset Name
2
0x9E TADDR_H
2
0x A0 TADDR_M
2
0x A2 TADDR_L
1
From SCC base address. SCC base = IMMR + 0x3D00 (SCC2) or 0x3E00 (SCC3) or 0x3F00 (SCC4)
2
The address should be written in little endian, not Freescale's big endian format (i.e., physical address
112233445566 should be written PADDR_L = 6655, PADDR_M = 4433, and PADDR_H = 2211.The TADDR
should be written in the same way as the PADDR.)
27.8 Programming the Ethernet Controller
The core configures 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 fields must be
programmed to special values for ethernet. Set DSR[SYN1] to 0x55 and DSR[SYN2] to 0xD5. 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).
27.9 SCC Ethernet Commands
Transmit and receive commands are issued to the CP command register (CPCR).
transmit commands.
Command
When used with the ethernet controller, this command violates a specific behavior of an
STOP TRANSMIT
ethernet/IEEE 802.3 station. It should not be used.
Used to ensure that transmission stops smoothly after the current frame finishes or has a collision.
GRACEFUL STOP
SCCE[GRA] is set once transmission stops, at which point ethernet transmit parameters and their
TRANSMIT
BDs can be updated. TBPTR points to the next TxBD. Transmission begins once the R bit of the next
BD is set and a
Note that if
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.
Enables transmission of characters on the transmit channel. The ethernet controller expects it after
RESTART
a
TRANSMIT GRACEFUL STOP TRANSMIT
resumes transmission from the current TBPTR in the channel TxBD table.
Initializes transmit parameters in this serial channel parameter RAM to reset state. Issue only when
INIT TX
the transmitter is disabled.
PARAMETERS
27-10
Width
Hword Allows addition and deletion of addresses from individual and group hash tables.
After placing an address in TADDR, issue a
TADDR_L (temp address low) is the least-significant half word and TADDR_H
(temp address high) is the most-significant half word.
Table 27-3. Transmit Commands
command is issued.
RESTART TRANSMIT
is issued and the current frame ends in a collision, TBPTR
GRACEFUL STOP TRANSMIT
command is issued or a transmitter error. The ethernet controller
and
INIT TX RX PARAMETERS
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Description
SET GROUP ADDRESS
Description
resets both transmit and receive parameters.
command.
Table 27-3 describes
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