Figure 2.23: PIC18F452 PORTB RB4–RB7 pins
Port pins RB4–RB7 can be used as interrupt-on-change inputs, whereby a change on any of pins 4 through 7 causes an interrupt flag to be set. The interrupt enable and flag bits RBIE and RBIF are in register INTCON.
In addition to PORTA and PORTB, the PIC18F452 has 8-bit bidirectional ports PORTC and PORTD, and 3-bit PORTE. Each port has its own data register (e.g., PORTC), data direction register (e.g., TRISC), and data latch register (e.g., LATC). The general operation of these ports is similar to that of PORTA.2.1.
In the PIC18F452 microcontroller PORTC is multiplexed with several peripheral functions as shown in Table 2.8. On a power-on reset, PORTC pins are configured as digital inputs.
Table 2.8: PIC18F452 PORTC pin functions
| Pin | Description |
|---|---|
| RC0/T1OSO/T1CKI | |
| RC0 | Digital I/O |
| T1OSO | Timer 1 oscillator output |
| T1CKI | Timer 1/Timer 3 external clock input |
| RC1/T1OSI/CCP2 | |
| RC1 | Digital I/O |
| T1OSI | Timer 1 oscillator input |
| CCP2 | Capture 2 input, Compare 2 and PWM2 output |
| RC2/CCP1 | |
| RC2 | Digital I/O |
| CCP1 | Capture 1 input, Compare 1 and PWM1 output |
| RC3/SCK/SCL | |
| RC3 | Digital I/O |
| SCK | Synchronous serial clock input/output for SPI |
| SCL | Synchronous serial clock input/output for I²C |
| RC4/SDI/SDA | |
| RC4 | Digital I/O |
| SDI | SPI data in |
| SDA | I²C data I/O |
| RC5/SDO | |
| RC5 | Digital I/O |
| SDO | SPI data output |
| RC6/TX/CK | |
| RC6 | Digital I/O |
| TX | USART transmit pin |
| CK | USART synchronous clock pin |
| RC7/RX/DT | |
| RC7 | Digital I/O |
| RX | USART receive pin |
| DT | USART synchronous data pin |
In the PIC18F452 microcontroller, PORTD has Schmitt trigger input buffers. On a power-on reset, PORTD is configured as digital input. PORTD can be configured as an 8-bit parallel slave port (i.e., a microprocessor port) by setting bit 4 of the TRISE register. Table 2.9 shows functions of PORTD pins.
Table 2.9: PIC18F452 PORTD pin functions
| Pin | Description |
|---|---|
| RD0/PSP0 | |
| RD0 | Digital I/O |
| PSP0 | Parallel slave port bit 0 |
| RD1/PSP1 | |
| RD1 | Digital I/O |
| PSP1 | Parallel slave port bit 1 |
| RD2/PSP2 | |
| RD2 | Digital I/O |
| PSP2 | Parallel slave port bit 2 |
| RD3/PSP3 | |
| RD3 | Digital I/O |
| PSP3 | Parallel slave port bit 3 |
| RD4/PSP4 | |
| RD4 | Digital I/O |
| PSP4 | Parallel slave port bit 4 |
| RD5/PSP5 | |
| RD5 | Digital I/O |
| PSP5 | Parallel slave port bit 5 |
| RD6/PSP6 | |
| RD6 | Digital I/O |
| PSP6 | Parallel slave port bit 6 |
| RD7/PSP7 | |
| RD7 | Digital I/O |
| PSP7 | Parallel slave port bit 7 |