LAPIS Semiconductor ML610421, User Manual, Page: 251 / 437

ML610Q421/ML610Q422/ML610421 User’s Manual
Chapter 18 Port 1
18 – 5
18.3 Description of Operation
18.3.1 Input Port Function
For each pin of Port 1, one of high-impedance input mode, input mode with a pull-down resistor, and input mode with a
pull-up resistor can be selected by setting the Port 1 control registers 0 and 1 (P1CON0 and P1CON1). At system reset,
high-impedance input mode is selected as the initial state.
The input level of the Port 1 pin can be read by reading the Port 1 data register (P1D).
18.3.2 Secondary Function
A high-speed crystal/ceramic oscillation pin or an external clock input pin is assigned to Port 1 as a secondary function.
Select high-speed crystal/ceramic oscillation mode or external clock input mode by using the high-speed clock mode
select function of the OSCM1 and 0 bits of the frequency control register 0 (FCON0). In crystal/ceramic oscillation
mode, both P10 and P11 pins are used as the pins for crystal/ceramic oscillation.
In external clock input mode, the P10 pin is used as the input pin of external clock and the P11 pin can be used as a
general-purpose input port.
Note:
No port mode register is provided for switching between the primary function and the secondary function of Port 1.
When using the Port 1 pins as high-speed oscillation pins, pin mode is switched according to the values set in the
OSCM1 and OSCM0 bits of the FCON0 register.
See Chapter 6, “Clock Generation Circuit,” for the details of the FCON0 register, high-speed oscillation, and external
clock input.