HD643303x Hitachi, HD643303x Datasheet - Page 372

• Manufacturer Part Number: HD643303x
• Description: Hitachi Microcomputer
• Manufacturer: Hitachi

Transmitting and Receiving Data
SCI Initialization (Synchronous 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 the TE bit to 0 sets the TDRE flag to 1 and
initializes TSR. Clearing the RE bit to 0, however, does not initialize the RDRF, PER, FER, and
ORE flags and RDR, which retain their previous contents.
Figure 11-15 is a sample flowchart for initializing the SCI.
CKE1, and CKE0 bits in SCR
Start transmitting or receiving
Set RIE, TIE, TEIE, MPIE,
Set TE or RE to 1 in SCR
(leaving TE and RE bits
Set RIE, TIE, TEIE, and
MPIE bits as necessary
Select communication
Start of initialization
Set value in BRR
Clear TE and RE
bits to 0 in SCR
format in SMR
cleared to 0)
1 bit interval
elapsed?
Yes
Figure 11-15 Sample Flowchart for SCI Initialization
Wait
No
1
2
3
4
1.
2.
3.
4.
Select the clock source in SCR. Clear the RIE, TIE, TEIE,
MPIE, TE, and RE bits to 0.
Select the communication format in SMR.
Write the value corresponding to the bit rate in BRR.
This step is not necessary when an external clock is used.
Wait for at least the interval required to transmit or receive
one bit, then set the TE or RE bit to 1 in SCR. Also set
the RIE, TIE, TEIE, and MPIE bits as necessary.
Setting the TE or RE bit enables the SCI to use the
TxD or RxD pin.
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