Motorola MPC8260 PowerQUICC II User Manual page 474

Part IV. Communications Processor Module
Table 14-5. SIxMR Field Descriptions (Continued)
Bits Name
13 GMx Grant mode for TDM a, b, c or d
0 GCI/SCIT mode. The GCI/SCIT D channel grant mechanism for transmission is internally
supported. The grant is one bit from the receive channel. This bit is marked by programming the
channel select bits of the SIx RAM with 0111 to assert an internal strobe on it. See
Section 14.7.2.2, ÒSCIT Programming.Ó
1 IDL mode. A grant mechanism is supported if the corresponding CMXSCR[GRx] bit is set. The
grant is a sample of L1GRx while L1TSYNCx is asserted. This grant mechanism implies the IDL
access controls for transmission on the D channel. See Section 14.6.2, ÒIDL Interface
Programming.Ó
14Ð15 TFSDx Transmit frame sync delay for TDM a, b, c or d. Determines the number of clock delays between the
transmit sync and the Þrst bit of the transmit frame. See Figure 14-16.
00 No bit delay. The Þrst bit of the frame is transmitted/received on the same clock as the sync.
01 1-bit delay
10 2-bit delay
11 3-bit delay
Figure 14-12 shows the one-clock delay from sync to data when xFSD = 01.
L1CLK
(CE=0)
L1SYNC
(FE=1)
Data
One-Clock Delay from Sync Latch to First Bit of Frame
Figure 14-12. One-Clock Delay from Sync to Data (xFSD = 01)
Figure 14-13 shows the elimination of the single-clock delay shown in Figure 14-12 by
clearing xFSD.
L1CLK
(CE=0)
L1SYNC
(FE=1)
Data
Figure 14-13. No Delay from Sync to Data (xFSD = 00)
14-20
Bit-0 Bit-1 Bit-2
Bit-0 Bit-1 Bit-2
No Delay from Sync Latch to First Bit of Frame
MPC8260 PowerQUICC II UserÕs Manual
Description
End of Frame
Bit-3 Bit-4 Bit-5
Bit-3 Bit-4 Bit-0
Bit-0
Bit-1 Bit-2
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