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MPC555
/
MPC556
QUEUED SERIAL MULTI-CHANNEL MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
14-66
14.9.6 Example QSCI1 Transmit for 17 Data Bytes
below shows a transmission of 17 data frames. The bold type indicates
the current value for QTPNT and QPEND. The italic type indicates the action just per-
formed by hardware. Regular type indicates the actions that should be performed by
software before the next event.
Figure 14-18 Queue Transmit Example for 17 Data Bytes
0000
0111
1000
1111
QTPNT
QPEND
1111
1000
0111
0000
QTSZ=1111 (16 Data Frames)
SCTQ[0]
SCTQ[7]
SCTQ[8]
SCTQ[15]
Write New QTSZ for When Wrap Occurs
QTSZ=0 (16+1=17),Set QTWE, Clear QTHE
Write SCTQ[0] for 17th Transfer
0000
0111
1000
1111
QTPNT
QPEND
0000
QTSZ=0000 (1 Data Frame)
SCTQ[0]
SCTQ[7]
SCTQ[8]
SCTQ[15]
Load QPEND with QTSZ (0)
Reset QTPNT
0000
0111
1000
1111
QTPNT
QPEND
1111
1000
0111
0000
QTSZ=1111 (16 Data Frames)
SCTQ[0]
SCTQ[7]
SCTQ[8]
SCTQ[15]
Data to beTransferred
Available Register Space
0001
1111
QTHE Interrupt Received
Transmit Queue Enabled
1
2
3
QBHE Interrupt Received
(Wrap Occurred)
Clear QTWE
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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