HD64F38024HV Datasheet, PDF (367/684 Pages) Renesas Technology Corp – Hardware Manual Renesas 8-Bit Single-Chip Microcomputer H8 Family/H8/300L Super Low Power Series

Section 10 Serial Communication Interface
Bits 1 and 0—Clock Enable 1 and 0 (CKE1, CKE0)
Bits 1 and 0 select the clock source and enabling or disabling of clock output from the SCK₃₂ pin.
The combination of CKE1 and CKE0 determines whether the SCK₃₂ pin functions as an I/O port,
a clock output pin, or a clock input pin.
The CKE0 bit setting is only valid in case of internal clock operation (CKE1 = 0) in asynchronous
mode. In synchronous mode, or when external clock operation is used (CKE1 = 1), bit CKE0
should be cleared to 0.
After setting bits CKE1 and CKE0, set the operating mode in the serial mode register (SMR).
For details on clock source selection, see table 10.9.
Bit 1
CKE1
Bit 0
CKE0
Communication Mode
Description
Clock Source
0
0
Asynchronous
Internal clock
Synchronous
Internal clock
0
1
Asynchronous
Internal clock
Synchronous
Reserved
1
0
Asynchronous
External clock
Synchronous
External clock
1
1
Asynchronous
Reserved
Synchronous
Reserved
Notes: 1. Initial value
2. A clock with the same frequency as the bit rate is output.
3. Input a clock with a frequency 16 times the bit rate.
SCK32 Pin Function
I/O port^*1
Serial clock output^*1
Clock output^*2
Clock input^*3
Serial clock input
Rev. 8.00 Mar. 09, 2010 Page 345 of 658
REJ09B0042-0800