Serial Management Controllers (SMCs)
MPC885 PowerQUICC Family Reference Manual, Rev. 2
29-24
Freescale Semiconductor
Figure 29-12. Synchronization with the TSA
Once SMCMR[REN] is set, the first time-slot after the frame sync causes the SMC receiver to achieve
synchronization. Data is received immediately, but only during defined receive time slots. The receiver
continues receiving data during its defined time slots until REN is cleared. If an
ENTER
HUNT
MODE
command is issued, the receiver loses synchronization, closes the buffer, and resynchronizes to the first
time slot after the frame sync.
Once SMCMR[TEN] is set, the SMC waits for the transmit FIFO to be loaded before trying to achieve
synchronization. If only a single time slot in a TDM frame is assigned to the SMC, USMC transmission,
as well as reception, is always synchronized to the beginning of that time slot. If multiple time slots in a
TDM frame are assigned to the SMC (as shown in
Figure 29-12
), then synchronization depends on the
order of initialization.
When the transmit FIFO is loaded, synchronization and transmission begins depending on the following:
•
If a buffer is made ready before the SMC is enabled, the first byte is placed in time slot 1 if CLEN
is 8 and to slot 2 if CLEN is greater than 8.
•
If a buffer is made ready after its SMC is enabled, the first byte can appear in any time slot
associated with this channel.
•
If a buffer is closed with BD[L] set, then the next buffer can appear in any time slot associated with
this channel.
TDM Tx CLK
TDM Tx SYNC
TDM Tx
After TEN
If SMC runs out of Tx buffers and new ones
are provided later, transmission begins at
is set,
transmission
begins here.
the beginning of either time slot.
SMC1
SMC1
TDM Rx CLK
TDM Rx SYNC
TDM Rx
After REN is set or after
ENTER
HUNT
MODE
command,
reception begins here.
SMC1
SMC1
Summary of Contents for PowerQUICC MPC870
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