Datasheet

Section 10 Serial Communication Interface
Rev. 8.00 Mar. 09, 2010 Page 345 of 658
REJ09B0042-0800
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 SCK
32
pin.
The combination of CKE1 and CKE0 determines whether the SCK
32
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.
Description
Bit 1
CKE1
Bit 0
CKE0 Communication Mode Clock Source SCK
32
Pin Function
0 0 Asynchronous Internal clock I/O port
*
1
Synchronous Internal clock Serial clock output
*
1
0 1 Asynchronous Internal clock Clock output
*
2
Synchronous Reserved
1 0 Asynchronous External clock Clock input
*
3
Synchronous External clock Serial clock input
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.