Very Simple Circuit but cannot work! Please help.

[JayJoe]

void initiate_main()
{
trisa=1; porta=0;
trisd=0; portd=0;

}

void main()
{
initiate_main();
while(1)
{
if(porta.f0==1)
{
portd.f0=1;
}

else
{
portd.f0=0;
}
}
}

What's wrong with the programming?

 

[Harald Kapp]

portd.f0 = 0 or 1, but the LED is on portb.
Either change the HW port of the assignment in the SW.

 

[JayJoe]

oh, i uploaded the wrong picture. anyway, stick with this circuit ive uploaded, even ive change the programming code to port b, it still doesnt work!

 

[Harald Kapp]

The programming seems o.k.
Is the oscillator running? Is the power supply o.k.? Is the LED in the correct orientation (short leg = cathode to ground)?

 

[JayJoe]

Ive found the answer. Port A cannot be input. It turns out working when i use port D as input. can anybody tell me why?

 

[Harald Kapp]

Port A cannot be input.

That should not be the case. PORT A should be useable as input or output, depending n the state of TRISA.

 

[JayJoe]

Hmm. I am thinking the same too, but it works using port d instead of port a. Still wondering.
Sorry that i'm still new to PIC, thanks for your reply.
Anyway, may i know the word 'TRIS' stands for?

 

[CDRIVE]

Hmm. I am thinking the same too, but it works using port d instead of port a. Still wondering.
Sorry that i'm still new to PIC, thanks for your reply.
Anyway, may i know the word 'TRIS' stands for?

I believe it means "Tri-State" Register. IE a port that can have one of 3 states. High (5V), Low(0V) or Open(Hi Z).

Chris

 

[davenn]

Anyway, may i know the word 'TRIS' stands for?

from this www site ..... http://www.mikroe.com/chapters/view/16/chapter-3-pic16f887-microcontroller/

3.3 INPUT/OUTPUT PORTS
In order to synchronize the operation of I/O ports with the internal 8-bit organization of the microcontroller, they are, similar to registers, grouped into five ports denoted by A, B, C, D and E. All of them have several features in common:

• For practical reasons, many I/O pins are multifunctional. If a pin performs any of these functions, it may not be used as a general-purpose input/output pin.
• Every port has its ‘satellite’, i.e. the corresponding TRIS register: TRISA, TRISB, TRISC etc. which determines the performance of port bits, but not their contents.

By clearing any bit of the TRIS register (bit=0), the corresponding port pin is configured as an output. Similarly, by setting any bit of the TRIS register (bit=1), the corresponding port pin is configured as an input. This rule is easy to remember 0 = Output, 1 = Input.



PORTA and TRISA register
Port A is an 8-bit wide, bidirectional port. Bits of the TRISA and ANSEL registers control the Port A pins. All Port A pins act as digital inputs/outputs. Five of them can also be analog inputs (denoted by AN):




Dave

 

[CDRIVE]

I love the graphics on the MikroElectronika website.

Chris

 

[JayJoe]

I believe it means "Tri-State" Register. IE a port that can have one of 3 states. High (5V), Low(0V) or Open(Hi Z).

Chris

Oh, tri-state. Thanks. May I know what do you mean by 'Open(Hi Z)'?

 

[JayJoe]

from this www site ..... http://www.mikroe.com/chapters/view/16/chapter-3-pic16f887-microcontroller/

3.3 INPUT/OUTPUT PORTS
In order to synchronize the operation of I/O ports with the internal 8-bit organization of the microcontroller, they are, similar to registers, grouped into five ports denoted by A, B, C, D and E. All of them have several features in common:

• For practical reasons, many I/O pins are multifunctional. If a pin performs any of these functions, it may not be used as a general-purpose input/output pin.
• Every port has its ‘satellite’, i.e. the corresponding TRIS register: TRISA, TRISB, TRISC etc. which determines the performance of port bits, but not their contents.

By clearing any bit of the TRIS register (bit=0), the corresponding port pin is configured as an output. Similarly, by setting any bit of the TRIS register (bit=1), the corresponding port pin is configured as an input. This rule is easy to remember 0 = Output, 1 = Input.

View attachment 21240

PORTA and TRISA register
Port A is an 8-bit wide, bidirectional port. Bits of the TRISA and ANSEL registers control the Port A pins. All Port A pins act as digital inputs/outputs. Five of them can also be analog inputs (denoted by AN):

View attachment 21241
Dave

Great. Now I understand better. Thanks for the website davenn!

 

[davenn]

Oh, tri-state. Thanks. May I know what do you mean by 'Open(Hi Z)'?

Hi Z = High Impedance

 

[jayanthd]

Try this code in your mikroC PRO PIC Compiler and it will work. If you have used 4 MHz crystal then select XT for Oscillator typr in edit project dialog box else choose HS.

void initiate_main()
{
    cmcon = 7;
    cvrcon = 0;
    adcon1 = 0x87;
    trisa = 1;
    porta = 0;
}

void main()
{
    initiate_main();
    delay_ms(200);

    while(1)
    {
        if(porta.f0 == 1)
        {
            delay_ms(50);
            if(porta.f0 == 1)
            {
                portd.f0 = 1;
            }
        }
        else if(porta.f0 == 0)
        {
            delay_ms(50);
            if(porta.f0 == 0)
            {
                portd.f0 = 0;
            }
        }
    }
}