PWM Update_function

Question

Dear Nordic Team

I have changed pwm driver example as you see in bellow . i also observed the codes which you linked for pwm. Bellow code works without the effect of update_pwm and working well. But the problem is that i can not control the duty cycle by void update_pwm function. Kindly please help me.

#include <stdio.h>
#include <string.h>
#include "nrf_drv_pwm.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "boards.h"
#include "bsp.h"
#include "app_timer.h"
#include "nrf_drv_clock.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
#include "nrf_delay.h"

static nrf_drv_pwm_t m_pwm0 = NRF_DRV_PWM_INSTANCE(0);


static uint16_t const              m_demo1_top  = 20000;
static uint16_t const              m_demo1_step = 200;
static uint8_t                     m_demo1_phase;
static nrf_pwm_values_individual_t m_demo1_seq_values;
static nrf_pwm_sequence_t const    m_demo1_seq =
{
    .values.p_individual = &m_demo1_seq_values,
    .length              = NRF_PWM_VALUES_LENGTH(m_demo1_seq_values),
    .repeats             = 0,
    .end_delay           = 0
};

static void demo1_handler(nrf_drv_pwm_evt_type_t event_type)
{
    if (event_type == NRF_DRV_PWM_EVT_FINISHED)
    {
        uint8_t channel    = m_demo1_phase >> 1;
        bool    down       = m_demo1_phase & 1;
        bool    next_phase = false;

        uint16_t * p_channels = (uint16_t *)&m_demo1_seq_values;
        uint16_t value = p_channels[channel];
        if (down)
        {
            value -= m_demo1_step;
            if (value == 0)
            {
                next_phase = true;
            }
        }
        else
        {
            value += m_demo1_step;
            if (value >= m_demo1_top)
            {
                next_phase = true;
            }
        }
        p_channels[channel] = value;

        if (next_phase)
        {
            if (++m_demo1_phase >= 2 * NRF_PWM_CHANNEL_COUNT)
            {
                m_demo1_phase = 0;
            }
        }
    }
}
static void pwm_init(void)
{
    NRF_LOG_INFO("Demo 1");

 

    nrf_drv_pwm_config_t const config0 =
    {
        .output_pins =
        {
            BSP_LED_0 | NRF_DRV_PWM_PIN_INVERTED, // channel 0
           
        },
        .irq_priority = APP_IRQ_PRIORITY_LOWEST,
        .base_clock   = NRF_PWM_CLK_1MHz,
        .count_mode   = NRF_PWM_MODE_UP,
        .top_value    = m_demo1_top,
        .load_mode    = NRF_PWM_LOAD_INDIVIDUAL,
        .step_mode    = NRF_PWM_STEP_AUTO
    };
    APP_ERROR_CHECK(nrf_drv_pwm_init(&m_pwm0, &config0, demo1_handler));


    APP_ERROR_CHECK(nrf_drv_pwm_simple_playback(&m_pwm0, &m_demo1_seq, 1,
                                      NRF_DRV_PWM_FLAG_LOOP));
}

void update_pwm(int16_t duty_cycle)
{
    m_demo1_seq_values.channel_0 = duty_cycle;
    nrf_drv_pwm_simple_playback(&m_pwm0, &m_demo1_seq, 1, 0);
}

int main(void)
{
    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));

    pwm_init();
    
    for (;;)
    {
    
    }
}

Kind regards

Sigurd · Accepted Answer

You can have 4 PWM channels for each instance, so you only need to create 1 instance.

Snippet:

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 */
/** @file
 * @defgroup pwm_example_main main.c
 * @{
 * @ingroup pwm_example
 *
 * @brief PWM Example Application main file.
 *
 * This file contains the source code for a sample application using PWM.
 */

#include <stdio.h>
#include <string.h>
#include "nrf_drv_pwm.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "boards.h"
#include "bsp.h"
#include "nrf_drv_clock.h"
#include "nrf_delay.h"


#define OUTPUT_PIN1 17
#define OUTPUT_PIN2 18
#define OUTPUT_PIN3 19

static nrf_drv_pwm_t m_pwm0 = NRF_DRV_PWM_INSTANCE(0);

// Declare variables holding PWM sequence values. In this example only one channel is used 
nrf_pwm_values_individual_t seq_values[] = {0, 0, 0, 0};
nrf_pwm_sequence_t const seq1 =
{
    .values.p_individual = seq_values,
    .length          = NRF_PWM_VALUES_LENGTH(seq_values),
    .repeats         = 0,
    .end_delay       = 0
};


// Set duty cycle between 0 and 100%
void pwm_update_duty_cycle(uint8_t duty_cycle_red , uint8_t duty_cycle_green , uint8_t duty_cycle_blue)
{
    
    //RED
    // Check if value is outside of range. If so, set to 100%
    if(duty_cycle_red >= 100)
    {
        seq_values->channel_0 = 100;// | 0x8000;
    }
    else
    {
        seq_values->channel_0 = duty_cycle_red;// | 0x8000;
    }

    
    //GREEN
    // Check if value is outside of range. If so, set to 100%
    if(duty_cycle_green >= 100)
    {
        seq_values->channel_1 = 100; // | 0x8000;
    }
    else
    {
        seq_values->channel_1 = duty_cycle_green; // | 0x8000;
    }

    //BLUE
    // Check if value is outside of range. If so, set to 100%
    if(duty_cycle_blue >= 100)
    {
        seq_values->channel_2 = 100; // | 0x8000;
    }
    else
    {
        seq_values->channel_2 = duty_cycle_blue; // | 0x8000;
    }
    
    nrf_drv_pwm_simple_playback(&m_pwm0, &seq1, 1, NRF_DRV_PWM_FLAG_LOOP);
}

static void pwm_init(void)
{
    nrf_drv_pwm_config_t const config0 =
    {
        .output_pins =
        {
            OUTPUT_PIN1, // channel 0
            OUTPUT_PIN2, // channel 1
            OUTPUT_PIN3, // channel 2
            NRF_DRV_PWM_PIN_NOT_USED,             // channel 3
        },
        .irq_priority = APP_IRQ_PRIORITY_LOWEST,
        .base_clock   = NRF_PWM_CLK_1MHz,
        .count_mode   = NRF_PWM_MODE_UP,
        .top_value    = 100,
        .load_mode    = NRF_PWM_LOAD_INDIVIDUAL,
        .step_mode    = NRF_PWM_STEP_AUTO
    };
    // Init PWM without error handler
    APP_ERROR_CHECK(nrf_drv_pwm_init(&m_pwm0, &config0, NULL));
}


int main(void)
{

    // Start clock for accurate frequencies
    NRF_CLOCK->TASKS_HFCLKSTART = 1; 
    // Wait for clock to start
    while(NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
    
    pwm_init();

    pwm_update_duty_cycle(20,50,80);

    for (;;)
    {
     __WFE;
    }
}


/** @} */

PWM Update_function

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