MPC555
/
MPC556
QUEUED SERIAL MULTI-CHANNEL MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
14-67
14.9.7 Example SCI Transmit for 25 Data Bytes
below is an example of a transmission of 25 data frames.
Figure 14-19 Queue Transmit Example for 25 Data Frames
0000
0111
1000
1111
QTPNT
QPEND
1111
1000
0111
0000
QTSZ=1111 (16 Data Frames)
SCTQ[0]
SCTQ[7]
SCTQ[8]
SCTQ[15]
0000
0111
1000
1111
QTPNT
QPEND
1000
QTSZ=1000 (9 Data Frames)
SCTQ[0]
SCTQ[7]
SCTQ[8]
SCTQ[15]
0000
0111
1000
1111
QTPNT
QPEND
1111
1000
0111
0000
QTSZ=1111 (16 Data Frames)
SCTQ[0]
SCTQ[7]
SCTQ[8]
SCTQ[15]
0001
0000
0111
1000
1111
QTPNT
QPEND
1000
QTSZ=1000 (9 Data Frames)
SCTQ[0]
SCTQ[7]
SCTQ[8]
SCTQ[15]
0000
0000
0001
Data to be Transferred
Available Register Space
1001
1111
QTHE Interrupt Received
Write QTSZ = 8 (16 + 9 = 25)
Write SCTQ [0:7] for 8 More Data Frames
Set QTWE
Clear QTHE
Load QPEND with QTSZ
Clear QTWE
Write SCTQ[8]
Clear QBHE
3
1
2
4
Transmit Queue Enabled
QBHE Interrupt Received
(Wrap Occurred)
Reset QTPNT
QTHE Interrupt Received
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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