SERIAL COMMUNICATION INTERFACE (SCI)
MOTOROLA
PORT C
6 - 51
of character frames until TE is set. (4) Write the first byte to follow the preamble into SRX
X:$FFF1
1
5
1
4
1
3
1
2
1
1
1
0
9
8
7
6
5
4
3210
0
0000
0
0
R
8
F
E
P
E
O
R
IDLE
RDRF
1
1
SCI ST
ATUS REGISTER (SSR)
(READ/WRITE)
0
1.
WHEN STX IS EMPTY
,
THEN
TDRE = 1.
2.
WHEN STX IS EMPTY AND
THE
TRANSMIT D
A
T
A SHIFT REGISTER IS EMPTY
THEN
TRNE = 1.
3.
IF
TIE = 1 IN SCR AND
TDRE = 1 IN SSR,
THEN AN INTERR
UPT IS GENERA
TED
.
TDRE
6
.
THE CHARA
CTER IN STX IS COPIED INT
O
TRANSMIT D
A
T
A SHIFT REGISTER.
TRNE IS CLEARED
.
TDRE IS SET
.
GO T
O
STEP
2
.
TRNE
23
16
15
8
7
0
X:$FFF6
X:$FFF5
X:$FFF4
STX
STX
STX
SCI TRANSMIT
D
A
T
A
P:$0018
INTERR
UPT VECT
OR T
ABLE
A
V
AILABLE FOR HOST COMMAND
TRANSMIT
INTERR
UPT
SER
VICE
R
OUTINE
4.
ST
ORE ONE
CHARA
CTER
INT
O STX (A)
5.
THIS CLEARS
TDRE IN SSR.
TXD
X:$FFF3
STXA
Figure 6-26 Asynchronous SCI Character Transmission
F
re
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sc
a
le
S
e
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I
Freescale Semiconductor, Inc.
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Go to: www.freescale.com
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c
.
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