Freescale Semiconductor MPC8260 - Manual (Page 1232)

FCC HDLC Controller
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
36-8 Freescale Semiconductor
The FPSMR fields are described in Table 36-6 .
0 3 4 5 6 8 9 10 15
Field NOF FSE MFF — TS —
Reset 0000_0000_0000_0000
R/W R/W
Addr 0x0x11304 (FPSMR1), 0x0x11324 (FPSMR2), 0x0x11324 (FPSMR3)
16 17 23 24 25 26 31
Field NBL — CRC —
Reset 0000_0000_0000_0000
R/W R/W
Addr 0x11306 (FPSMR1), 0x11326 (FPSMR2), 0x11326 (FPSMR3)
Figure 36-3. HDLC Mode Register (FPSMR)
Table 36-6. FPSMR Field Descriptions
1
Bits Name Description
0–3 NOF Number of flags. Minimum number of flags between or before frames (0–15 flags). If NOF = 0000,
no flags are inserted between the frames. Thus, for back-to-back frames, the closing flag of one
frame is immediately followed by the opening flag of the next frame.
4 FSE Flag sharing enable. This bit is valid only if GFMR[RTSM] is set.
0 Normal operation
1 If NOF = 0000, a single shared flag is transmitted between back-to-back frames. Other values of
NOF are decremented by 1 when FSE is set. This is useful in signaling system #7 applications.
5 MFF Multiple frames in FIFO. Setting MFF applies only when in RTS mode (GFMR x [RTSM] = 1).
0 Normal operation. The transmit FIFO buffer must never contain more than one HDLC frame. The
CTS lost status is reported accurately on a per-frame basis. The receiver is not affected by this
bit.
1 The transmit FIFO buffer can contain multiple frames, but lost CTS is not guaranteed to be
reported on the exact buffer/frame it occurred on. This option, however, can improve the
performance of HDLC transmissions for small back-to-back frames or if the user prefers to
strongly limit the number of flags sent between frames. MFF does not affect the receiver.
Refer to note 1 at the end of this table.
7–8 — Reserved, should be cleared.
9 TS Time stamp
0 Normal operation.
1 A 32-bit time stamp is added at the beginning of the receive BD data buffer, thus the buffer pointer
must be (32-byte aligned - 4). The BD’s data length does not include the time stamp. See
Section 14.3.8, “RISC Time-Stamp Control Register (RTSCR) .”
10–15 — Reserved, should be cleared.