5
Serial Ports
5 – 41
Autobuffering only consumes the cycles necessary to perform the data
transfer; no additional cycles are lost fetching instructions. The above
diagram assumes that all instructions and data transfers occur in one
CLKOUT
EXEC
Sync Delay
Expand RX0
COMPAND
Continue Main Program
Request
SPORT1 Receive
Request
SPORT0 Receive
EXPAND RX0
EXPAND RX1
A
B
C
AUTOBUFFER
D
AUTOBUFFER
Expand RX1
RX0 Autobuffer Transfer
RX1 Autobuffer Transfer
Figure 5.38 Receive Companding Example With Both Serial Ports
processor cycle.
5.13.9 Receive Companding Latency
In addition to the cycles used for synchronization, there are some
additional delays possible due to receive companding. The synchronized
request is used by the processor to decide when to write the receive
CLKOUT
EXEC
INT
FETCH INT
E
AUTOBUFFER
Sync Delay
NOP Instruction, Fetch Vector
Execute First Instruction Of Interrupt Routine
D
Figure 5.39 Autobuffering Interrupt Example