Hello
I have a general question for Port pin initialization. We set PORT to low or high using the PORT or LAT register

Sensor connected to Port B Pin 7
Led connected to Port C Pin 7

If I set PORTB = 0; PORTC = 0;

When the sensor is in high states it sends 5v to Port B Pin 7 and when It is in low states it sends 0v to Port B Pin 7

What will happens if I set PORTB = 1; PORTC = 1;

 

First you need to sort out TRIS to decide which pins will be outputs and inputs.
In general read the port state from the PORT register and write port values to the LAT register.

 

What micro are you using?

 

If you are using a PIC, 8-bit MCU, the ports come up as analog inputs. You need to set to digital (ANSEL) and output or input as desired (TRIS). You may also need to turn off comparators, if present.

 

Each pin is set as either an input or an output by the TRIS register for that port. If a pin is an input, it does not matter what the micro writes to the LAT register, it is ignored. And, to repeat what others have said, do not write to the PORT register. It can cause unexpected effects.

To be pedantic, it is only a read / modify / write operation that is problematic, a write to the whole port works correctly. But get in the habit of writing only to the LAT register to avoid mistakes.

Bob

 

What LAT register? We don't even know the make, much less model number of the MCU.

 

For example,
Sensor connected to Port B Pin 7
Led connected to Port C Pin 7

PORTx register- Read or write to PORTx
LATx register. - Write to PORTx
TRISx - Configure as input or output

If I set
TRISB = 0x80; TRISC = 0x80;
PORTB = 0x00; LATC = 0x00;

PORTB = 0x00; What will happens if I set PORTB = 0xff; ?

What will happen if i set PORTx = 0 or PORTx = 1

 

To the OP: are you aware that the variety of possible micros is huge? What is exactly a PIC 8 for you?

Why do you think I asked in post #3 to say what micro are you using?

 

PORTB = 0x00; What will happens if I set PORTB = 0xff; ?

What will happen if i set PORTx = 0 or PORTx = 1

PORTx = 0 probably clears the port. PORTx = 1 may only set bit<0> =1. I think PORTx = 0xFF is a safer way to set all bits to 1. Remember, not all ports of your device may be 8 bits. If it's a PIC16F1829, and the port is only bits<4..7> P0RTx = 1 may not do anything.

You really do need to tell us the device you are using for meaningful responses.

 

What LAT register? We don't even know the make, much less model number of the MCU.

From the title: “PIC 8” an in the original post “PORT and LAT registers.

That is enough for me to answer the question.

Bob

 

What will happen if i set PORTx = 0 or PORTx = 1

Read my first post, #5, and you will know.

Bob