CC2530: Internal Pull up/down Resistors - What does Bit [7:0] mean?

I tried doing the below to set P1_6 as an input with Pulldown, but it doesn't seem to work. I connect P1_6 to 3v, and then I disconnected them for this test. I set a breakpoint in the "HAL_ENTER_ISR" of hal_key.c to see if the breakpoint is hit, and it is always hitting periodically on its own even though P1_6 is disconnected from 3v. Do I need to reset the pin or something? How can I fix this?

P1SEL &= ~( BV(6) );
P1INP &= ~( BV(6) );
P2INP |= ( BV(6) );

I also noticed that when I pressed the button, the breakpoint is hit. And when I release the button, the breakpoint is also hit again. Why is this happening with the internal resistor, and how can I make it only read when I press the button (rising edge)?

Hal_key.c provides key interrupt example for this and I suggest you to study it.

Ok. Can you answer the other question to please ("Do I need to reset the pin or something? How can I fix this?")?

When you want to enable interrupt in hal_key.c, I remember I told you that you have to define ISR_KEYINTERRUPT in your project. Do you define ISR_KEYINTERRUPT?

Yes.

Can you show me a screen shot about where you set the breakpoint?

What is your define of HAL_KEY_SW_3_PXIFG and HAL_KEY_CPU_PORT_1_IF?

/* SW_3 is at P1.6 */
#define HAL_KEY_SW_3_PORT P1
#define HAL_KEY_SW_3_BIT BV(6)
#define HAL_KEY_SW_3_SEL P1SEL
#define HAL_KEY_SW_3_DIR P1DIR

/* edge interrupt */
#define HAL_KEY_SW_3_EDGEBIT BV(2)
#define HAL_KEY_SW_3_EDGE HAL_KEY_RISING_EDGE

/* SW_2 interrupts */
#define HAL_KEY_SW_3_IEN IEN2 /* CPU interrupt mask register */
#define HAL_KEY_SW_3_IENBIT BV(4) /* Mask bit for all of Port_1 */
#define HAL_KEY_SW_3_ICTL P1IEN /* Port Interrupt Control register */
#define HAL_KEY_SW_3_ICTLBIT BV(6) /* P0IEN - P1.6 enable/disable bit */
#define HAL_KEY_SW_3_PXIFG P1IFG /* Interrupt flag at source */

The code looks fine. I suggest you to use scope to check if there is noise on P1.6 to cause the ISR keep triggering.

I noticed that when I do P1INP = 0, after the ISR is triggered, then the ISR doesn't trigger again. It seems to act like some sort of reset. Can you explain why this seems to work? Is this a correct thing to do after ISR is triggered?

P1INP is Port 1 Input Mode and 0 means Pullup or pulldown which depends on P2INP settings. I suspect this is still about the noise on your P1.6 of HW.

Adding external pulldown resistor seems to fix problem, but the intent off this project is to utilize the internal chip's pulldown resistor. I don't think noise is a problem. I checked with scope too.

If you intend to use internal pulldown, you have to set P1INP and P2INP.

I mentioned how I did that earlier, but here it is again.

P1SEL &= ~( BV(6) );
P1INP &= ~( BV(6) );
P2INP |= ( BV(6) );

So, is the problem solved?

No. From here, when I press the P1_6 button, the input is read. However, (as I said before) the input consistently reads as being pressed even though I released the button - "consistent input reading" .

I tried doing "P1INP = 0" after the input had been read to reset the pin, and the "consistent input reading" stopped. So when I press P1_6, the input is read, and not read again and again.

Adding "P1INP = 0" seems to be my solution to prevent the "consistent input reading". However I wanted to ask you what exactly does doing "P1INP = 0" actually do and why does this seem to solve my problem?

If you add external pull down, does the problem fixed?

Yes. But my intent is to use the internal pulldown resistor instead of an external one. Could you answer my previous question please.

I suppose you only need to set "P1INP &= ~( BV(6) );" and "P2INP |= ( BV(6) );" to use P1.6 as internal pull down.

I think my question was "However I wanted to ask you what exactly does doing "P1INP = 0" actually do and why does this seem to solve my problem?". Could you answer this question please?

P1INP is Port 1 Input Mode and value 0 means Pullup or pulldown.