HD6473032F16 Datasheet, PDF (477/847 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

Section 13 Serial Communication Interface
Bits 1 and 0—Clock Enable 1 and 0 (CKE1/0): These bits select the SCI clock source and
enable or disable clock output from the SCK pin. Depending on the settings of CKE1 and CKE0,
the SCK pin can be used for generic input/output, serial clock output, or serial clock input.
The CKE0 setting is valid only in asynchronous mode, and only when the SCI is internally
clocked (CKE1 = 0). The CKE0 setting is ignored in synchronous mode, or when an external
clock source is selected (CKE1 = 1). Select the SCI operating mode in SMR before setting the
CKE1 and CKE0 bits. For further details on selection of the SCI clock source, see table 13.9 in
section 13.3, Operation.
Bit 1: Bit 0:
CKE1 CKE0 Description
0
0
Asynchronous mode Internal clock, SCK pin available for generic
input/output^*1
Synchronous mode Internal clock, SCK pin used for serial clock output^*1
1
Asynchronous mode Internal clock, SCK pin used for clock output^*2
Synchronous mode Internal clock, SCK pin used for serial clock output
1
0
Asynchronous mode External clock, SCK pin used for clock input^*3
Synchronous mode External clock, SCK pin used for serial clock input
1
Asynchronous mode External clock, SCK pin used for clock input^*3
Synchronous mode External clock, SCK pin used for serial clock input
Notes: 1. Initial value
2. The output clock frequency is the same as the bit rate.
3. The input clock frequency is 16 times the bit rate.
Rev. 3.00 Mar 21, 2006 page 447 of 814
REJ09B0302-0300