Freescale Semiconductor MPC8260 - Manual (Page 855)

Multi-Channel Controllers (MCCs)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 28-7
28.3.1.1 Internal Transmitter State (TSTATE)—HDLC Mode
Internal transmitter state (TSTATE) is a 4-byte register provides transaction parameters associated with
SDMA channel accesses (like function code registers) and starts the transmitter channel.
To start the channel, write 0xHH800000 to TSTATE, where HH is the TSTATE high byte (see
Figure 28-2 ). When the channel is active, the CP changes the value of the three LSBs, hence these 3 bytes
must be masked if the user reads back the TSTATE.
TSTATE high-byte fields are described in Table 28-3 .
0x38 MFLR Hword Maximum frame length register. Defines the longest expectable frame for this channel.
(64-Kbyte maximum). The remainder of a frame that is larger than MFLR is discarded
and the LG flag is set in the last frame’s BD. An interrupt request might be generated
(RXF and RXB) depending on the interrupt mask. A frame’s length is considered to be
everything between flags, including CRC. No more data is written into the current buffer
when the MFLR violation is detected.
0x3A MAX_CNT Hword Max_length counter, used by the CP (read-only for the user)
0x3C RCRC Word Temp receive CRC, used by the CP (read-only for the user)
1
The offset is relative to dual-port RAM (DPRAM) base address + 64*CH_NUM
0 1 2 3 4 5 6 7
Field — GBL BO TC2 DTB BDB
Reset —
R/W R/W
Figure 28-2. TSTATE High Byte
Table 28-3. TSTATE High-Byte Field Descriptions
Bits Name Description
0–1 — Reserved, should be cleared.
2 GBL Global. Setting GLB activates snooping (only the 60X bus can be snooped, this parameter is ignored
for local bus transactions).
3–4 BO Byte ordering. Set BO to select the required byte ordering for the buffer. If BO is changed on-the-fly,
it takes effect at the beginning of the next frame or at the beginning of the next BD.
00 Reserved
01 Munged little-endian.
1x Big-endian
5 TC2 Transfer code. Contains the transfer code value of TC[2], used during this SDMA channel memory
access. TC[0–1] is driven with a 0b11 to identify this SDMA channel access as a DMA-type access.
Table 28-2. Channel-Specific Parameters for HDLC (continued)
Offset
1
Name Width Description