CC2540 when Advertising or Connected interferes with Timer 1 PWM signal ?

Alex B

Other Parts Discussed in Thread: CC2540

Hi,

We are currently using the CC2540 with Timer 1 generating a PWM signal (module mode - set output on compare, clear on zero). Also, we have an input from an external signal that periodically resets the Timer 1.

By looking at the scope it looks that when the CC2540 is advertising or connected (radio link is active) the Timer 1 looks like jittering and it's phase is impacted.

Is this possible? Link layer timing activity taking precedent over other functions or else?

If so, how can be managed? Unfortunately our application requires advertising and PWM signal generation at the same time.

Thanks!

Alex

over 13 years ago

0 Albert Skog over 13 years ago

TI__Prodigy 300 points

I have the same problem!! No fix yet though. I have been told the cpu is halted while the radio is on, seemingly stopping the timers as well, which would explain the behavior.

http://e2e.ti.com/support/low_power_rf/f/538/p/196614/701217.aspx#701217

Did you by any chance test using some older version of the stack?

0 Alex B over 13 years ago in reply to Albert Skog

Intellectual 260 points

Thanks a lot, Albert. Well, good to know at least our observations are consistent. I observed same behavior in BLE stack 1.1, did not try w/ older ones.

Perhaps we can have someone from TI to comment here?

Alex

0 Albert Skog over 13 years ago in reply to Alex B

TI__Prodigy 300 points

Alex, do a Ctrl-Shift-F for

HCI_EXT_ClkDivOnHaltCmd( HCI_EXT_ENABLE_CLK_DIVIDE_ON_HALT );

Turns out I had this lying around from the SimpleBLEPeripheral example...

0 Alex B over 13 years ago in reply to Albert Skog

Intellectual 260 points

Thanks a lot, Albert!

Definitely helped, not sure the problem is gone. Did it completely resolve the issue in your case?

Alex

0 Albert Skog over 13 years ago in reply to Alex B

TI__Prodigy 300 points

That's weird, it did remove all the jitter for me. What sort of orders of magnitude are we talking here? I had a 1.5ms pulse occasionally jumping up to ~3ms, are you perhaps doing some faster stuff? Did you disable POWER_SAVING?

0 Alex B over 13 years ago in reply to Albert Skog

Intellectual 260 points

Nope, my pulses are in same order, but it looks OK most of the time. I will do some more investigation as they issue may be elsewhere.

Did you have to sync your PWM signal with an external input of similar order of milliseconds or not?

Thanks for your good tip! I will definitely mark it as verified answer!

Alex

0 Albert Skog over 13 years ago in reply to Alex B

TI__Prodigy 300 points

No, mine is output only.. What I did in order to verify that my setup was to comment out the GAP initialization calls in my app so that it ran without BLE. That way I concluded my app was "working" and the problems were from somewhere on the stack side. Not sure if you can try your stuff out without radio? If possible it should give you a hint where to keep looking..

0 Melih Karakelle over 11 years ago in reply to Albert Skog

Prodigy 200 points

Did you find any solution for this problem?

I guess i have similar problem here: http://e2e.ti.com/support/low_power_rf/f/538/t/319822.aspx

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CC2540 when Advertising or Connected interferes with Timer 1 PWM signal ?