Freescale Semiconductor MPC8260 - Manual (Page 896)

Multi-Channel Controllers (MCCs)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
28-48 Freescale Semiconductor
3. Program the SI’s SIRAM and related registers. If the user wishes to enable the TDM at this time,
the SIRAM programming cannot yet contain MCC-related timeslots. Those timeslots should be
NULL entries and not programmed for MCC usage until after MCC-related initialization is
complete. Refer to
Chapter 15, “Serial Interface with Time-Slot Assigner,” for SI programming
details.
4. Initialize buffer descriptors and data buffers as needed.
5. Initialize all MCC global parameters.
6. Initialize MCC channel-specific parameters for channels to be used. (Note that, if SI was not
already enabled in step 3, TSTATE and RSTATE can be fully programmed here to begin data
transmission and reception as soon as the TDM is enabled. If a user wishes to wait until after the
TDM is enabled before starting data transmission and reception, the user may program only the
FCR portions of RSTATE and TSTATE; and STOP TX and STOP RX commands should be issued
for the appropriate channels before enabling the TDM.)
7. Initialize MCC channel-extra parameters for channels to be used.
8. Initialize Superchannel Table if superchannels are to be used.
9. Issue MCC INIT commands as appropriate to make sure all MCC FIFOs that are to be used are
initialized.
10. Enable TDM (or if TDM is already enabled, the user may now reprogram the TDM to include
MCC-related timeslots).
11. If the user did not program a channel’s TSTATE and RSTATE in step 6 to begin data transmission
and reception immediately upon having an active TDM, the user may program the start conditions
at this time.
NOTE
Some steps may be performed out of order. However, it is critical, regardless
of their relative sequence, that steps 5, 6, 7, 8 and 9 occur before the
enabling of the TDM or an active TDM is reprogrammed to include
MCC-related timeslots. Failure to properly initialize MCC parameters and
issue appropriate INIT commands before MCC-related timeslots are
programmed in an active TDM may result in spurious GUN events or other
anomalous behavior.
28.10.1 Stopping and Restarting a Single-Channel
The following sequence must be followed to stop a single channel in order to change the MCC parameters
of the respective channel:
1. Issue a STOP command for the respective channel as described in Section 28.7, “MCC
Commands,” or change the associated SI RAM entry to point to a channel which is not active and
wait for two frame periods in order to clear the internal FIFOs.
2. Change the channel parameters.
3. Enable the MCC channel(s) as described in Section 28.3.1.1, “Internal Transmitter State
(TSTATE)—HDLC Mode,” and Section 28.3.1.4, “Internal Receiver State (RSTATE)—HDLC
Mode,” or change the associated SI RAM entry to point to the respective channel.