CHAPTER 13 UART
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Block Diagram of the UART-relating Pins
When use of the pull-up resistor is selected in the pull-up setting register, the pin status does not become
Hi-Z but "H" level (pull-up state) in stop mode (SPL = 1). However, the pull-up resistor is not applied
during reset; accordingly, the pin status becomes Hi-Z.
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Figure 13.3-1 Block Diagram of UART-relating Pins
PDR
PDR read
PDR read
(At read-modify-write)
Output
latch
PDR write
DDR
DDR write
Stop mode
(SPL = 1)
PUL read
PUL
PUL write
UCK
UI
Stop mode
(SPL = 1)
Resource output
Resource
Resource
output
output allowed
enable
P30/UCK/SCK
P32/UI/SI
Pull-up resistor
Pch
Pin
P30/UCK/SCK
Nch
P31/UO/SO
P32/UI/SI