P2/ P2_1 cannot be set

Josh Eckhoff

Other Parts Discussed in Thread: CC2540

I am trying to manually set the High/Low on different pins programically for my cc2540/1. I have tried to use the individual bits of P0/P1/P2, and the more direct P2_1.

No matter how I try it, the values start as P2 = 1 and P2_1 = 0 and after

P2_1 = 1;

P2 = 2;

It never changes the actual value, they stay at P2 = 1 and P2_1 = 0.

I have been able to set P0DIR correctly though.

Any advice is welcome.

over 9 years ago

0 YiKai Chen over 9 years ago

Guru 735455 points

I am not sure what you intend to do. Let me tell you what I know. If you want to set P0.1 to high, you should set "P0SEL &= (~BV(1));", "P0DIR |= BV(1);", and "P0_1=1;". Then, if you want to set it to low, just use "P0_1=0;".

0 Josh Eckhoff over 9 years ago in reply to YiKai Chen

Intellectual 450 points

Ill use your example:

P0_1 defaults to 1
if I have the code "P0_1=0;"
the value of P0_1 remains 1, when it should now be 0.

0 YiKai Chen over 9 years ago in reply to Josh Eckhoff

Guru 735455 points

Can you set a breakpoint at P0_1=0 and check the register value of P0DIR and P0SEL?

0 Josh Eckhoff over 9 years ago in reply to YiKai Chen

Intellectual 450 points

P0SEL and P0DIR both start at 0
I have tried changing them to 1's but that doesn't change my issue

0 YiKai Chen over 9 years ago in reply to Josh Eckhoff

Guru 735455 points

Since your P0DIR is 0, it means that you P0.1 is set to GPI not GPO. So, it is no effect when you set P0_1=1.

0 Josh Eckhoff over 9 years ago in reply to YiKai Chen

Intellectual 450 points

Ok, I figured out my issue with P0 and P1.

If you set P0DIR = 0xFF; (All Input) it forces all bit to a HIGH value (1) and it cannot be changed at all. If you set it to P0DIR = 0; (All Output) you can change any value LOW(0) or HIGH(1)

This also is true for P1, but if we go back to my original question. I was asking about P2_1.

The only P2 bit I can change is P2_0, the rest are stuck on '0' no matter what I do.

P2SEL = 0;
P2DIR = 0xFF;

P2_4 = 1;
P2_3 = 1;
P2_2 = 1;
P2_1 = 1;
P2_0 = 1; // Only one that changes

P2_4 = 0;
P2_3 = 0;
P2_2 = 0;
P2_1 = 0;
P2_0 = 0; // Only one that changes

0 Fredrik K over 9 years ago in reply to Josh Eckhoff

TI__Guru** 106705 points

Hi Josh,

I would recommend reading through the GPIO chapter in the user guide: www.ti.com/.../swru191 .

Cheers,
Fredrik

0 YiKai Chen over 9 years ago in reply to Josh Eckhoff

Guru 735455 points

P2.1 and P2.2 are supposedly connected to debugger pins and won't be used as GPIO. As Fredrik's suggest, you should check CC254x user guide for details.