Toshiba H1 Series Data Book page 177

3.7.23 Port X (PX4, PX5 and PX7)
Port X5 and X7 are 2-bit general-purpose I/O ports. Each bit can be set individually for
input or output. Resetting sets port X5 and X7 to input port and output latch to "0". In
addition to functioning as general-purpose I/O port pins, PX5 and PX7 can also function as
USB clock input pin
Above setting is used the control register PXCR and function register PXFC.
Port X4 is 1-bit general-purpose output port. Resetting sets output latch to "0". In
addition to functioning as general-purpose output port, PX4 can also function as system
clock output pin (CLKOUT) and output pin (LDIV). This setting is used the PX register
and function register PXFC.
Reset
Function
control
(on bit basis)
PXFC write
R
Output latch
PX write
PX read
CLKOUT output
LDIV output
(X1USB).
S
A
Selector
B
S
A
Selector
B
Figure 3.7.63 Port X4
92CZ26A-174
TMP92CZ26A
PX4 (CLKOUT)
(LDIV)