LAPIS Semiconductor ML610421, User Manual, Page: 281 / 437

ML610Q421/ML610Q422/ML610421 User’s Manual
Chapter 21 Port 4
21 – 11
21.3 Description of Operation
21.3.1 Input/Output Port Functions
For each pin of Port 4, either output or input is selected by setting the Port 4 direction register (P4DIR).
In output mode, high-impedance output mode, P-channel open drain output mode, N-channel open drain output mode,
or CMOS output mode can be selected by setting the Port 4 control registers 0 and 1 (P4CON0 and P4CON1).
In input mode, high-impedance input mode, input mode with a pull-down resistor, or input mode with a pull-up resistor
can be selected by setting the Port 4 control registers 0 and 1 (P4CON0 and P4CON1).
At a system reset, high-impedance output mode is selected as the initial state.
In output mode, “L” or “H” level is output to each pin of Port 4 depending on the value set by the Port 4 data register
(P4D).
In input mode, the input level of each pin of Port 4 can be read from the Port 4 data register (P4D).
21.3.2 Secondary and Tertiary Functions
Secondary and tertiary functions are assigned to Port 4 as the I2C bus 0 pins (SDA, SCL), UART 0 pins (RXD0, TXD0),
RC-ADC (channel 1) oscillation pins (IN1, CS1, RS1, RT1), synchronous serial port 0 pins (SIN0, SCK0, SOUT), and
the PWM output pin (PWM0). These pins can be used in a secondary or tertiary function mode by setting the
P47MD0 to P40MD0 bits and the P47MD1 to P40MD1 bits of the Port 4 mode registers (P4MOD0, P4MOD1).
Note:
The P44 to P47 pins of port 4 are configured as pins dedicated to the RC-ADC function during A/D conversion.
Therefore, if there is any unused pin, that pin cannot be used during A/D conversion. For the RC-ADC, see Chapter 24,
“RC Oscillation Type A/D Converter”.