PWM on nrf52840

RE: PWM on nrf52840

Einar Thorsrud — Fri, 27 Nov 2020 08:50:17 GMT

Hi,

5000 is the period in micro seconds. So the frequency will be 1 / 5000e-6 s = 200 Hz.

RE: PWM on nrf52840

vietanhkt24 — Fri, 27 Nov 2020 05:07:59 GMT

hey bro, can you expland why 5000L = 200Hz ? I really don't understand. Thank you bro

RE: PWM on nrf52840

Einar Thorsrud — Mon, 03 Feb 2020 08:34:24 GMT

The driver code (implementation) is provided as-is, and not intended to be used. When it comes to the WPM driver example that is also quite complex but remembers that the PWM peripheral is most sensible for more complex signals since it can "play out" a waveform from RAM via DMA etc. If you just want a simple to use PWM implementation then the PWM library is just as good in most cases (provided you have available TIMER, PPI and GPIOTE channels).

RE: PWM on nrf52840

Einar Thorsrud — Mon, 03 Feb 2020 08:31:41 GMT

Hi,

This for loop creates the breathing effect by having the duty cycle change slowly.

RE: PWM on nrf52840

saver — Sun, 02 Feb 2020 07:27:42 GMT

pwm driver is better or pwm library is better?

why the pwm driver has 600 lines of code

can i get some simpler pwm driver code.

RE: PWM on nrf52840

saver — Sun, 02 Feb 2020 06:17:25 GMT

In pwm library i have some doubt to some commands

err_code = app_pwm_init(&PWM1,&pwm1_cfg,pwm_ready_callback);
APP_ERROR_CHECK(err_code);

and what are these things for

for (uint8_t i = 0; i < 40; ++i)
{
value = (i < 20) ? (i * 5) : (100 - (i - 20) * 5);

what is the purpose of this?

RE: PWM on nrf52840

Einar Thorsrud — Fri, 31 Jan 2020 14:26:36 GMT

Hi,

If you just want a simple PWM system, then you can use the PWM library. The example uses two breathing LEDs, but you can simplify it to one fixed LED glowing with 50 % intensity. Then the example could reduce to this:

#include <stdbool.h>
#include <stdint.h>
#include "nrf.h"
#include "app_error.h"
#include "bsp.h"
#include "nrf_delay.h"
#include "app_pwm.h"

APP_PWM_INSTANCE(PWM1,1);                   // Create the instance "PWM1" using TIMER1.

int main(void)
{
    ret_code_t err_code;

    /* 1-channel PWM, 200Hz, output on DK LED 1 pin. */
    app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_1CH(5000L, BSP_LED_0);

    /* Switch the polarity of the second channel. */
    pwm1_cfg.pin_polarity[0] = APP_PWM_POLARITY_ACTIVE_HIGH;

    /* Initialize and enable PWM. */
    err_code = app_pwm_init(&PWM1,&pwm1_cfg, NULL);
    APP_ERROR_CHECK(err_code);
    app_pwm_enable(&PWM1);

    /* Set duty cycle to 50 % */
    while (app_pwm_channel_duty_set(&PWM1, 0, 50) == NRF_ERROR_BUSY);

    while (true)
    {
    }
}

RE: PWM on nrf52840

saver — Fri, 31 Jan 2020 14:08:32 GMT

can you give me a more simpler code the documentation is some what tough to understand.

RE: PWM on nrf52840

Patrick — Thu, 30 Jan 2020 13:26:29 GMT

PWM Library Documentation

PWM Driver Documentation

RE: PWM on nrf52840

saver — Thu, 30 Jan 2020 13:22:57 GMT

they are actually really hard to understand,

can you give me a simpler code

(OR)

where can i get the meaning or purpose for the commands given in the PWM library or pwm driver?

RE: PWM on nrf52840

Patrick — Thu, 30 Jan 2020 13:17:19 GMT

Have you taken a look at the pwm examples included with the SDK? Particularly pwm_driver and pwm_library?