
MB90560 series
CHAPTER 8 I/O PORTS
205
G
Port operation after a reset
When the CPU is reset, the DDR4 register is initialized to “0”. As a result, the output buffer is
turned off (I/O mode changes to input), the pins are placed in a high impedance state.
The PDR4 register is not initialized when the CPU is reset. To use the port in output mode,
therefore, output mode must be specified in the DDR4 register after the output data is set in
the PDR4 register.
G
Port operation in stop or time-base timer mode
If the pin state setting bit (SPL) in the low-power mode control register (LPMCR) is already “1”
when the port is shifted to stop or time-base timer mode, the port pins are placed in a high-
impedance state. This is because the output buffer is turned off forcibly regardless of the value
in the DDR4 register.
<Caution>
Note that the inputs are fixed at a certain level to prevent leakage due to an open circuit.
Table 8.7-4 lists the states of the port 4 pins.
Table 8.7-4 States of port 4 pins
SPL : Pin state setting bit of low-power mode control register (LPMCR)
Hi-z : High impedance
Pin
Normal operation
Sleep mode
Stop mode or time-
base timer mode
(SPL = 0)
Stop mode or time-
base timer mode
(SPL = 1)
Hardware standby
mode
P40/SIN0~P47/
ATG
General-purpose
I/O port
General-purpose I/
O port
General-purpose I/O
port
Input shut down/
output in Hi-z
Input shut down/output
in Hi-z