HD6432646 Hitachi, HD6432646 Datasheet - Page 515

• Manufacturer Part Number: HD6432646
• Description: (HD64F264x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

Eight serial clock pulses are output in the transfer of one character, and when no transfer is
performed the clock is fixed high. When only receive operations are performed, however, the
serial clock is output until an overrun error occurs or the RE bit is cleared to 0. If you want to
perform receive operations in units of one character, you should select an external clock as the
clock source.
Data Transfer Operations:
SCI initialization (clocked synchronous mode)
Before transmitting and receiving data, you should first clear the TE and RE bits in SCR to 0,
then initialize the SCI as described below.
When the operating mode, transfer format, etc., is changed, the TE and RE bits must be cleared
to 0 before making the change using the following procedure. When the TE bit is cleared to 0,
the TDRE flag is set to 1 and TSR is initialized. Note that clearing the RE bit to 0 does not
change the contents of the RDRF, PER, FER, and ORER flags, or the contents of RDR.
Figure 13-15 shows a sample SCI initialization flowchart.
Note: In simultaneous transmit and receive operations, the TE and RE bits should both be cleared
Set TE and RE bits in SCR to 1, and
set RIE, TIE, TEIE, and MPIE bits
Clear TE and RE bits in SCR to 0
Set CKE1 and CKE0 bits in SCR
to 0 or set to 1 simultaneously.
Set data transfer format in
1-bit interval elapsed?
Start initialization
Set value in BRR
SMR and SCMR
<Transfer start>
(TE, RE bits 0)
Figure 13-15 Sample SCI Initialization Flowchart
Yes
Wait
No
[4]
[2]
[3]
[1]
[1] Set the clock selection in SCR. Be sure
[2] Set the data transfer format in SMR
[3] Write a value corresponding to the bit
[4] Wait at least one bit interval, then set
to clear bits RIE, TIE, TEIE, and MPIE,
TE and RE, to 0.
and SCMR.
rate to BRR. Not necessary if an
external clock is used.
the TE bit or RE bit in SCR to 1.
Also set the RIE, TIE, TEIE, and MPIE
bits.
Setting the TE and RE bits enables the
TxD and RxD pins to be used.
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