HD64F2145 Datasheet, PDF (431/829 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

15.9.8 Notes on Switching from SCK Pins to Port Pins
When SCK pins are switched to port pins after transmission has completed, pins are enabled for
port output after outputting a low pulse of half a cycle as shown in figure 15.28.
SCK/Port
Data
TE
C/
CKE1
Bit 6
CKE0
Low pulse of half a cycle
1. Transmission end
Bit 7
2. TE = 0
4. Low pulse output
3. C/ = 0
Figure 15.28 Switching from SCK Pins to Port Pins
To prevent the low pulse output that is generated when switching the SCK pins to the port pins,
specify the SCK pins for input (pull up the SCK/port pins externally), and follow the procedure
below with DDR = 1, DR = 1, C/$ = 1, CKE1 = 0, CKE1 = 0, and TE = 1.
1. End serial data transmission
2. TE bit = 0
3. CKE1 bit = 1
4. C/$ bit = 0 (switch to port output)
5. CKE1 bit = 0
SCK/Port
Data
TE
C/
Bit 6
CKE1
CKE0
1. Transmission end
Bit 7
2. TE = 0
3. CKE1 = 1
High output
4. C/ = 0
5. CKE1 = 0
Figure 15.29 Prevention of Low Pulse Output at Switching from SCK Pins to Port Pins
Rev. 2.0, 08/02, page 391 of 788