Re: [Zephyr-users] Buggy PWM driver for nRF52

Chettimada, Vinayak Kariappa

Hi Vikrant,


Please try the PWM without the BT Controller included. There could be some PWM regression due to changes in controller implementation.

That said the nrf5_sw  driver is software variant designed for older nRF51 SoCs. For newer nRF52x series h/w PWM’s should be used.


Nrf5_sw will work provided careful mitigation of used PPI and timers between the driver and BT controller use.


Which SoC are you using?





From: zephyr-devel-bounces@... [mailto:zephyr-devel-bounces@...] On Behalf Of Vikrant More
Sent: Thursday, February 08, 2018 5:04 AM
To: Marti Bolivar <marti@...>
Cc: zephyr-users@...; zephyr-devel@...; Felipe Neves <ryukokki.felipe@...>
Subject: Re: [Zephyr-devel] [Zephyr-users] Buggy PWM driver for nRF52


Hi Marti,

>>Are you using the latest master?



On Thu, Feb 8, 2018 at 1:23 AM, Marti Bolivar <marti@...> wrote:

Hi Vikrant,


Are you using the latest master?


Three improvements to nRF PWM went in fairly recently:


3f1dbfda1 pwm: nrf5_sw: don't disable timer if another channel is still active

ab399a1cf pwm: nrf5_sw: do not use 'inversed' polarity by default

cec073c35 pwm: nrf5_sw: add support for SYS_LOG





On Wed, Feb 7, 2018 at 1:59 PM, Vikrant More <vikrant8051@...> wrote:

I took reference of $zephy/samples/samples/fade_led project


& add following parameters in my prj.conf


Could you please inform me, what I should do besides this ??
Thank You !!


On Feb 7, 2018 11:36 PM, "Felipe Neves" <ryukokki.felipe@...> wrote:

Hi Vikrant,

Did you configure what pins are associated to pwm duty_cycles on the menuconfig?





2018-02-07 10:15 GMT-02:00 Vikrant More <vikrant8051@...>:

Hello World !!

I've added following lines in my project main ()

    pwm_dev = device_get_binding(PWM_DRIVER);

    if (!pwm_dev)
        printk("Cannot find %s!\n", PWM_DRIVER);

        if(pwm_pin_set_usec(pwm_dev, PWM_CHANNEL0, PERIOD, pulse_width0))
            printk("pwm pin set fails\n");

        if(pwm_pin_set_usec(pwm_dev, PWM_CHANNEL1, PERIOD, pulse_width1))
            printk("pwm pin set fails\n");


And using bluetooth updating value of pulse_width0 & pulse_width1. Those two are defined as global variables.

pulse_width0 --> LED_1 on nrf52840_PDK
pulse_width1 --> LED_2 on nrf52840_PDK

I'm able to update value of both these variables using Bluetooth.

I used printk to check it. My logic is perfect.

But if I vary pulse_width0 then it affects intensity of LED2
& if I vary pulse_width1 then it affects intensity of LED1.

Why ? Is anyone found this BUG ?

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Felipe S. Neves 

Embedded software & systems engineer

Skype: fneves1989

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