This document discusses I/O port programming for PIC microcontrollers. It explains that each port has three special function registers (PORTx, TRISx, and LATx) that control the port's direction and output. The TRIS register is used to configure a port as an input or output by writing 1s or 0s. Reading from the PORT register returns the pin states, while writing to LATx sets the output pin values. Single bit instructions allow accessing individual pins within ports in a bit-addressable manner.

1. I/O port programming (PIC)

2. PIC 18 – I/O ports

3. PIC18F458
Alternative functions of Ports
• ADC
• Timers
• Interrupts
• Serial communication

4. PORT SFRs
• Each port has three (3) SFRs associated with it.
• PORTx
• TRISx (TRIState)
• LATx (LATch)

5. TRIS register role
• This makes a given port an input or output port.
• Output  write 0s to TRISx (0 stands for Out)
• Input  write 1s to TRISx (1 stands for In)
• Unless we activate TRISx bits (set to 0s), the data will not go from port
register to the pins of PIC.
• Ex:

6. TRIS register role
• Get data from PORTC and send it to PORTB

7. Different ways to do same things

8. Read followed by write I/O operation
Alternative Method

9. Ports status upon reset

10. Bit addressability
• Single-Bit (Bit oriented) instruction

11. Bit addressability

12. Bit addressability

13. Bit addressability

14. Bit addressability

15. Summary