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: /** * Copyright (c) 2015 - 2017, Nordic Semiconductor ASA * * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * 2. Redistributions in binary form, except as embedded into a Nordic * Semiconductor ASA integrated circuit in a product or a software update for * such product, must reproduce the above copyright notice, this list of * conditions and the following disclaimer in the documentation and/or other * materials provided with the distribution. * * 3. Neither the name of Nordic Semiconductor ASA nor the names of its * contributors may be used to endorse or promote products derived from this * software without specific prior written permission. * * 4. This software, with or without modification, must only be used with a * Nordic Semiconductor ASA integrated circuit. * * 5. Any software provided in binary form under this license must not be reverse * engineered, decompiled, modified and/or disassembled. * * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ /** @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 #include #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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