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CHAPTER 13 UART
Block Diagram of the UART-relating PinsFigure 13.3-1 Block Diagram of UART-relating PinsWhen use of the pull-up resistor is selected in the pull-up setting register, the pin status does not becomeHi-Z but "H" level (pull-up state) in stop mode (SPL = 1). However, the pull-up resistor is not appliedduring reset; accordingly, the pin status becomes Hi-Z.
DDR
Pch
Nch
UCK
PDR
PUL
P30/UCK/SCK
P32/UI/SI
UI
P30/UCK/SCK
P31/UO/SO
Pin
P32/UI/SI

Internal data bus

PDR read
PDR read
(At read-modify-write)
PDR write
DDR write
PUL read
PUL write
Resource output
Resource
output
enable
Stop mode
(SPL = 1)
Resource
output allowed
Pull-up resistor
Output
latch
Stop mode
(SPL = 1)