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0
D0
D1
D2
D3
D4
D5
D6
D7
0/1
1
1
1 frame
Figure 11-3 Phase Relationship between Output Clock and Serial Data
(Asynchronous Mode)
Transmitting and Receiving Data
SCI Initialization (Asynchronous Mode): Before transmitting or receiving, clear the TE and
RE bits to 0 in SCR, then initialize the SCI as follows.
When changing the communication mode or format, always clear the TE and RE bits to 0 before
following the procedure given below. Clearing TE to 0 sets the TDRE flag to 1 and initializes
TSR. Clearing RE to 0, however, does not initialize the RDRF, PER, FER, and ORER flags and
RDR, which retain their previous contents.
When an external clock is used, the clock should not be stopped during initialization or
subsequent operation. SCI operation becomes unreliable if the clock is stopped.
Figure 11-4 shows a sample flowchart for initializing the SCI.
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