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Section 13 Serial Communication Interface
SCK
t
TDRE
Note: In operation with an external clock source, be sure that t >4 states.
Figure 13.22 Example of Synchronous Transmission Using DMAC
Switching from SCK Pin Function to Port Pin Function:
• Problem in Operation: When switching the SCK pin function to the output port function (high-
level output) by making the following settings while DDR = 1, DR = 1, C/A = 1, CKE1 = 0,
CKE0 = 0, and TE = 1 (synchronous mode), 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 13.23)
SCK/port
Data
Bit 6
TE
C/A
CKE1
CKE0
Figure 13.23 Operation when Switching from SCK Pin Function to Port Pin Function
Rev. 4.00 Jan 26, 2006 page 538 of 938
REJ09B0276-0400
D0
D1
D2
1. End of transmission
Bit 7
2.TE= 0
D3
D4
D5
Half-cycle low-level output
4. Low-level output
3.C/A= 0
D6
D7
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