16.10.8 Notes On Switching From Sck Pins To Port Pins; Figure 16.43 Switching From Sck Pins To Port Pins; Figure 16.44 Prevention Of Low Pulse Output At Switching From Sck Pins To Port Pins - Renesas H8S/2158 User Manual

Section 16 Serial Communication Interface (SCI, IrDA, and CRC)

16.10.8 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 16.43.
SCK/Port
Bit 6
Data
TE
C/A
CKE1
CKE0
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/A = 1, CKE1 = 0, CKE1 = 0, and TE = 1.
1. End serial data transmission
2. TE bit = 0
3. CKE1 bit = 1
4. C/A bit = 0 (switch to port output)
5. CKE1 bit = 0
SCK/Port
Data
Bit 6
TE
C/A
CKE1
CKE0

Figure 16.44 Prevention of Low Pulse Output at Switching from SCK Pins to Port Pins

Rev. 3.00 Jan 25, 2006 page 466 of 872
REJ09B0286-0300
1. Transmission end
Bit 7
2. TE = 0

Figure 16.43 Switching from SCK Pins to Port Pins

1. Transmission end
Bit 7
2. TE = 0
Low pulse of half a cycle
4. Low pulse output
3. C/A = 0
4. C/A = 0
3. CKE1 = 1
High output
5. CKE1 = 0