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MPC555
/
MPC556
QUEUED SERIAL MULTI-CHANNEL MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
14-62
Figure 14-15 Queue Transmitter Block Enhancements
14.9.4 QSCI1 Additional Transmit Operation Features
• Available on a single SCI channel (SCI1) implemented by the queue transmit en-
able (QTE) bit set by software. When enabled, (QTE = 1) the TDRE bit should be
ignored by software and the TC bit is redefined (as described later).
• When the queue is disabled (QTE = 0), the SCI functions in single buffer transfer
mode where the queue size is set to one (QTSZ = 0000), and TDRE and TC func-
tion as previously defined. Locations SCTQ[0:15] can be used as general pur-
pose 9-bit registers. All other bits pertaining to the queue should be ignored by
software.
• Programmable queue up to 16 transmits (SCTQ[0:15]) which may allow for infi-
nite and continuous transmits.
• Available transmit wrap function to prevent message breaks for transmits greater
10 (11) - BIT
Tx Shift Register
ST
OP
ST
AR
T
H (8) 7 6 5 4 3 2 1 0 L
TxD
SCTQ[0]
SCTQ[1]
SCTQ[15]
9-bi
t 1
6
:1
Mu
x
Transmitter
Baud Rate
Clock
4-bits
QT
S
Z
[0
:3]
QT
H
E
I
QB
HE
I
Queue Control
QT
E
QPEND[0
:3
]
QT
HE
QB
HE
QT
W
E
Queue Status
Queue Control
Logic
SCI Interrupt Request
SC1DR Tx BUFFER
SCI1 Non-Queue Operation
data bus
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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