HD6432633 Datasheet, PDF (819/1453 Pages) Renesas Technology Corp – Series of Microcomputers (MCUs: microcomputer units)

Switching from SCK Pin Function to Port Pin Function:
• Problem in Operation: When switching the SCK pin to the output function while DDR and DR
are set to 1 and clock synchronous SCI clock output is being used, low-level output occurs for
one half-cycle, followed by port output.
When switching to the port function by making the following settings while DDR, DR, and
C/A are set to 1 and CKE1, CKE0, and TE are set to 0, low-level output occurs for one half-
cycle.
1. End of serial data transmission
2. TE bit = 0
3. C/A bit = 0 ... switchover to port output
4. Occurrence of low-level output (see figure 16-29)
Half-cycle low-level output
SCK/port
Data
Bit 6
TE
C/A
1. End of transmission
Bit 7
2.TE= 0
4. Low-level output
3.C/A = 0
CKE1
CKE0
Figure 16-29 Operation when Switching from SCK Pin Function to Port Pin Function
765