Unable to configure Port 1 as input.

[Nitesh Dubey]

Dear Team,

Greetings,

I am facing a problem for configuring Port 1 as input. I have connected a push button on P1.4 and an led on P0.0. I want to perform a simple task, i.e. when I press button then LED must turn on, else LED must be off. I have used NRF24LE1, 32 pin package.

#include "reg24le1.h"

void main()
{
	P0DIR = 0x00;  // set PORT0 as output
	P1DIR = 0xff;  // set PORT1 as input
	while(1)  // infinite loop
	{
		if (P1 == 0x10)     // check P1.4 is high
		{
			P0 = 0x01;
		}
		else
		{
			P0 = 0x00;
		}
	}
}

[Håkon Alseth]

Hi,

 

Do you have an external pull resistor on P1.4?

It looks like your button is active high, so you can try to configure a pull-down resistor on P1.4 using P1CON register:

 

Pull-up example: P1CON = (0x50 | pin), for P1.4: P1CON = 0x54;

Pull-down example: P1CON = (0x30 | pin), for P1.4: P1CON = 0x34;

 

Kind regards,

Håkon

[Nitesh Dubey]

I have tried with pull down resister but problem is still the same.

[Håkon Alseth]

Try this, in case other inputs are set high as well:

if (P1 & 0x10)     // check P1.4 is high

 

Kind regards,

Håkon

[Nitesh Dubey]

Not solved !!!

#include "reg24le1.h"

void main()
{
	P0DIR = 0x00;  // set PORT0 as output
	//P1DIR = 0xff;  // set PORT1 as input
	P1CON = 0x50;
	while(1)  // infinite loop
	{
		if (P1 & 0x10)     // check P1.4 is high
		{
			P0 = 0x01;
		}
		else
		{
			P0 = 0x00;
		}
	}
}

[Håkon Alseth]

You placed a pull-down on P1.0 by calling "P1CON=0x30;"

Please see my former comment and check the datasheet on how to correctly set pull-down on P1.4.

 

Kind regards,

Håkon