IBM PowerPC 405GP User Manual page 542

12:13 TFS Transmit (TX) FIFO Size
00 Reserved
01 1 KB
102 KB
11 Reserved
14
Reserved Always zero
15:16 TRO Transmit Request 0 Defines the different modes for using
00 Single packet
transmit channel 0 of EMAC.
01 Multiple packets
10 Dependent mode (bits 17: 18 must also
be programmed to 10)
11 Reserved
17:18 TR1
Transmit Request 1
Defines the different modes for using
00 Single packet
transmit channel 1 of EMAC.
01 Multiple packets
10 Dependent mode (bits 15:16 must also
be programmed to 10)
11 Reserved
19:31 Reserved
19.7.3 Transmit Mode Register 0 (EMACO_TMRO)
EMACO_ TMRO defines EMAC operating modes during transmit operations (see "EMAC Transmit
Operation" on page 19-5).
EMACO_ TMRO[GNPO, GNP1 , GNPD] are self-clearing. Writing 0 to these fields has no effect.
GNPOGNFD
+ +
t t
311
GNP1 FC
Figure 19·17. Transmit Mode Register 0 (EMACO_TMRO)
0 GNPO Get New Packet 0 EMACO_TMRO[GNPO]
=
0 if.EMAC is
o
Writing 0 has no effect.
programmed in dependent mode.
1 Packet ready for transmission on TX
Channel 0
1 GNP1 Get New Packet 1 EMACO_TMRO[GNP1]
=
0 if EMAC is
o
Writing 0 has no effect.
programmed in dependent mode.
1 Packet ready for transmission on TX
Channel 1
2 GNPD Get New Packet for Dependent Mode EMACO_TMRO[GNPD]
=
0 if EMAC is not
o
Writing 0 to this bit has no effect
programmed in dependent mode.
1 Packet ready for transmission in
EMACO_ TMRO[GNPD]
=
1 activates the
dependent mode
EMAC transmit path in dependent mode.
Preliminary Ethernet Media Access Controller 19-27