RE: NRF52 Dim LED with PWM Driver

Nestor Matas — Thu, 21 Sep 2017 08:41:41 GMT

Very useful, thanks!

RE: NRF52 Dim LED with PWM Driver

Bndit — Sat, 20 May 2017 17:55:56 GMT

Thank you for your kindness.

RE: NRF52 Dim LED with PWM Driver

ovrebekk — Thu, 18 May 2017 12:07:10 GMT

Hi Bndit

I just updated the answer with a new version of the example that compiles under SDK v13.

RE: NRF52 Dim LED with PWM Driver

Bndit — Tue, 16 May 2017 10:36:15 GMT

Not compiling, too many errors such as APP_TIMER_TICKS gets too many arguments

RE: NRF52 Dim LED with PWM Driver

Bryan H — Fri, 04 Nov 2016 16:07:42 GMT

Thank you for your help! This helped a lot.

RE: NRF52 Dim LED with PWM Driver

Stefan Birnir Sverrisson — Mon, 24 Oct 2016 16:52:17 GMT

Hi Bryan

Yeah, I must agree with you, the pwm_driver example in SDK 12.1.0 has a lot of parameters. I figured out how things worked by looking at image 2 in the PS PWM chapter to realize that there is a counter that counts up to the specified top value, which is one pwm period, and then repeats the sequence.

I have attached a simplified (hopefully) example which is more or less the code presented in the pwm_driver documentation. Example output: Light intensity on LED_1 on the nRF52-DK is gradually increased and that sequence is repeated 4 times.

How it works:

base_clock runs at 1MHz and the top value is 1000. This means that the base clock ticks every 1 us and the top value is reached every 1us*1000=1ms
The seq_values array includes 10 values. The first value in the array (value 0) is repeated 100 times (.repeats = 100), this means that the duty cycle is 0% for 1us* 1000* 100=100ms
The next value is also repeated 100 times, i.e. for 100ms, namely the value 100, which gives 10% duty cycle
After the last value has run for its 100ms, we delay it extra 500ms (end_delay = 500) before repeating the whole sequence

We can make this sequence repeat forever by setting

nrf_drv_pwm_simple_playback(&m_pwm0, &seq, 4, NRF_DRV_PWM_FLAG_LOOP);

or play the sequence only 4 times with

nrf_drv_pwm_simple_playback(&m_pwm0, &seq, 4, NRF_DRV_PWM_FLAG_STOP);

There is not much more to this example. The BSP is initialized and the bsp_evt_handler is defined so you can insert any code for desired button action into this handler.

pwm_driver_simple.zip

An updated version of the example that compiles in SDK v13 can be found here:
pwm_driver_simple_sdk13.zip