Proper sequence to initialize PWM?

RE: Proper sequence to initialize PWM?

Susheel Nuguru — Tue, 21 Jul 2015 06:46:57 GMT

sometimes it helps to do a side by side comparision and sometimes it doesn't. it is mostly timing with PWM so you need to compare the registers in the GPIOTE interrupt handler. may be you can post your full main.c file here and we can have a look. Which version of SD and SDK are you using?

RE: Proper sequence to initialize PWM?

nszmnsky — Fri, 17 Jul 2015 15:23:37 GMT

Sorry, meant to say I was writing down on paper what the register values were. I just did side by side comparison using screen grabs instead and am not seeing a difference in how the GPIOTE, TIMER2 are set up. For GPIO the PIEZO pin settings are a match, and for PPI things match except for CHEN group which appears to get set to 0x80000000 during advertising start. Any value to posting these bitmaps?

RE: Proper sequence to initialize PWM?

Susheel Nuguru — Fri, 17 Jul 2015 14:33:48 GMT

No that is not a reliable way. Do not deviate your usage from what PWM recommended. Else it will become like what compiler standard says "ITS UNPREDICTABLE BEHAVIOR"

RE: Proper sequence to initialize PWM?

nszmnsky — Fri, 17 Jul 2015 13:21:35 GMT

Thanks for the update. However even moving pwm_init to end of main after all other inits doesn't seem to work. I've been trying to check out peripheral register values between the PWM example (modified to match my settings) and my app. I'm looking at GPIO, GPIOTE, PPI, & TIMER2. So far I'm not seeing a difference but I'm doing it manually by writing values seen in the two apps so may not be reliable.

RE: Proper sequence to initialize PWM?

Susheel Nuguru — Fri, 17 Jul 2015 07:34:50 GMT

nszmnsky, This dependency is there. I missed to see it. Krzysztof agreed to investigate if it is needed and probably remove the dependency in the future. I think this case can rest until then as he knows most about it.

RE: Proper sequence to initialize PWM?

Krzysztof Chruscinski — Fri, 17 Jul 2015 06:58:39 GMT

It's not mentioned in the documentation but PWM should be initialized after SoftDevice. The thing is that PWM is using PPI driver which if softdevice is present access PPI through softdevice. It's recommended to initialize softdevice as one of the first things in the main().

RE: Proper sequence to initialize PWM?

nszmnsky — Thu, 16 Jul 2015 21:58:15 GMT

The before ble_stack_init comment was in "Pwm and softdevice on nRF5822" but on re-reading saw later comment from submitter that said after - after everything in fact. So is there a dependency/conflict that I'm not aware of?

RE: Proper sequence to initialize PWM?

Susheel Nuguru — Thu, 16 Jul 2015 14:24:57 GMT

Hi nszmnsky

Where does it say that it should be before ble_stack_init? I do not think that there is such dependency. you code works fine when i tried it here. Make sure you are sampling the right pin