PWM consume high power near 300uA

[khodidas]

Hi,

I am using SDK15.3.0 and s132_nrf52_6.1.1_softdevice.  (nRF52832)

Getting higher current consumption (300uA) while using the PWM library. (https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/pwm_example.html)

Also tried to generate using PPI, But the same result as PWM library.

I wonder when used a low-power PWM library and got 460uA. (https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/low_power_pwm_example.html) 

200uA somewhat expected as per the datasheet, But is there any other way to generate PWM using low power? (<200uA)

Thanks,

Nirav Patel

[Sigurd]

Hi,

 

200uA somewhat expected as per the datasheet

 This is for the PWM peripheral, but as mentioned in the PS, it does not include GPIO, DMA current. I don't think clock current is part of this either. But PWM library and low_power_pwm_example does not use the PWM peripheral.

What PWM frequency and duty cycle do you need ?

[khodidas]

Sigurd,

I got another code from the below link by using this ability to generate PWM using RTC with <30uA (Frequency 1kHz)

https://devzone.nordicsemi.com/f/nordic-q-a/32673/current-consumption-rtc--ppi---gpiote-on-nrf52

Did minor modification to generate PWM with different duty cycle (1 to 99%). Used COMPARE_1 to handle it.

In between, I observed that sometimes getting inverted PWM output when changing CC value of COMPARE_1 to change duty cycle.

Ex. Duty cycle change to 20%, with 20% duty cycle it must be HIGH for 20% and LOW for rest 80% but when the issue occurred it will be HIGH for 80% and LOW for 20%.

May be issue occurred because the pin configured to do the TOGGLE operation.

void gpiote_config(void)
{
    ret_code_t err_code = NRF_SUCCESS;
    
    err_code = nrf_drv_gpiote_init();
    APP_ERROR_CHECK(err_code);
    
    nrf_drv_gpiote_out_config_t config = GPIOTE_CONFIG_OUT_TASK_TOGGLE(true);
    
    err_code = nrf_drv_gpiote_out_init(GPIO_OUTPUT_PIN_NUMBER, &config);
    APP_ERROR_CHECK(err_code);
    
    nrf_drv_gpiote_out_task_enable(GPIO_OUTPUT_PIN_NUMBER);
    
}

/** @brief Function for initializing the PPI peripheral.
*/
void ppi_init(void)
{
    uint32_t err_code = NRF_SUCCESS;

    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_ppi_channel_alloc(&ppi_channel);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_ppi_channel_assign(ppi_channel,
                                          nrf_rtc_event_address_get(rtc.p_reg, NRF_RTC_EVENT_COMPARE_0),
                                          nrf_drv_gpiote_out_task_addr_get(GPIO_OUTPUT_PIN_NUMBER));
    APP_ERROR_CHECK(err_code);
    
    err_code = nrf_drv_ppi_channel_fork_assign(ppi_channel, nrf_rtc_task_address_get(rtc.p_reg, NRF_RTC_TASK_CLEAR));
    APP_ERROR_CHECK(err_code);
	
	/* Modification */
	err_code = nrf_drv_ppi_channel_alloc(&ppi_channel2);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_ppi_channel_assign(ppi_channel2,
                                          nrf_rtc_event_address_get(rtc.p_reg, NRF_RTC_EVENT_COMPARE_1),
                                          nrf_drv_gpiote_out_task_addr_get(_pwmPin));
    APP_ERROR_CHECK(err_code);
	/* END */

    // Enable both configured PPI channels
    err_code = nrf_drv_ppi_channel_enable(ppi_channel);
    APP_ERROR_CHECK(err_code);
	/* Modification */
	err_code = nrf_drv_ppi_channel_enable(ppi_channel2);
    APP_ERROR_CHECK(err_code);
	/* END */
}

Can we configure the pin to set high while CC_0 event and low when CC_1 compared?

Like, configure the same pin in "NRFX_GPIOTE_CONFIG_OUT_TASK_LOW" and NRFX_GPIOTE_CONFIG_OUT_TASK_HIGH".

In this way, I can fix the issue of an inverted waveform.

void gpiote_config(void)
{
    ret_code_t err_code = NRF_SUCCESS;
    
    err_code = nrf_drv_gpiote_init();
    APP_ERROR_CHECK(err_code);
    
    nrf_drv_gpiote_out_config_t config = GPIOTE_CONFIG_OUT_TASK_HIGH;
	nrf_drv_gpiote_out_config_t config1 = GPIOTE_CONFIG_OUT_TASK_LOW;
    
    err_code = nrf_drv_gpiote_out_init(GPIO_OUTPUT_PIN_NUMBER, &config);
    APP_ERROR_CHECK(err_code);
	err_code = nrf_drv_gpiote_out_init(GPIO_OUTPUT_PIN_NUMBER, &config1);
    APP_ERROR_CHECK(err_code);
    
    nrf_drv_gpiote_out_task_enable(GPIO_OUTPUT_PIN_NUMBER);
    
}

Is it possible?

Thanks,

Nirav Patel

[Sigurd]

khodidas said:

Is it possible?

Yes. Try something like this:

/**
 * Copyright (c) 2014 - 2021, 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 rtc_example_main main.c
 * @{
 * @ingroup rtc_example
 * @brief Real Time Counter Example Application main file.
 *
 * This file contains the source code for a sample application using the Real Time Counter (RTC).
 *
 */

#include "nrf.h"
#include "nrf_gpio.h"
#include "nrf_drv_rtc.h"
#include "nrf_drv_clock.h"
#include "boards.h"
#include "app_error.h"
#include <stdint.h>
#include <stdbool.h>
#include "nrf_drv_gpiote.h"
#include "nrf_drv_ppi.h"


#define USE_PPI 1

#define GPIO_OUTPUT_PIN_NUMBER 3

// Set RTC2_ENABLED to 1 in sdk_config.h
static nrf_drv_rtc_t rtc = NRF_DRV_RTC_INSTANCE(2); /**< Declaring an instance of nrf_drv_rtc for RTC2. */
static nrf_ppi_channel_t ppi_channel;s
static nrf_ppi_channel_t ppi_channel2;

void rtc_event_handler(nrf_drv_rtc_int_type_t int_type)
{
    nrf_drv_rtc_disable(&rtc);
    nrf_drv_rtc_counter_clear(&rtc);
    nrf_drv_rtc_int_enable(&rtc, NRF_RTC_INT_COMPARE0_MASK);
    nrf_drv_rtc_enable(&rtc);
    
    nrf_gpio_pin_toggle(GPIO_OUTPUT_PIN_NUMBER);
}


/** @brief Function starting the internal LFCLK XTAL oscillator.
 */
static void lfclk_config(void)
{
    ret_code_t err_code = nrf_drv_clock_init();
    APP_ERROR_CHECK(err_code);

    nrf_drv_clock_lfclk_request(NULL);
}

void gpio_config(void)
{
    nrf_gpio_cfg_output(GPIO_OUTPUT_PIN_NUMBER);
}

void gpiote_config(void)
{
    ret_code_t err_code = NRF_SUCCESS;
    
    err_code = nrf_drv_gpiote_init();
    APP_ERROR_CHECK(err_code);
    
    nrf_drv_gpiote_out_config_t config = GPIOTE_CONFIG_OUT_TASK_TOGGLE(true);
    
    err_code = nrf_drv_gpiote_out_init(GPIO_OUTPUT_PIN_NUMBER, &config);
    APP_ERROR_CHECK(err_code);
    
    nrf_drv_gpiote_out_task_enable(GPIO_OUTPUT_PIN_NUMBER);
    
}

/** @brief Function for initializing the PPI peripheral.
*/
void ppi_init(void)
{
    uint32_t err_code = NRF_SUCCESS;

    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_ppi_channel_alloc(&ppi_channel);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_ppi_channel_assign(ppi_channel,
                                          nrf_rtc_event_address_get(rtc.p_reg, NRF_RTC_EVENT_COMPARE_0),
                                          nrf_drv_gpiote_out_task_addr_get(GPIO_OUTPUT_PIN_NUMBER));
    APP_ERROR_CHECK(err_code);


    	/* Modification */
	err_code = nrf_drv_ppi_channel_alloc(&ppi_channel2);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_ppi_channel_assign(ppi_channel2,
                                          nrf_rtc_event_address_get(rtc.p_reg, NRF_RTC_EVENT_COMPARE_1),
                                          nrf_drv_gpiote_out_task_addr_get(GPIO_OUTPUT_PIN_NUMBER));
    APP_ERROR_CHECK(err_code);
	/* END */

            err_code = nrf_drv_ppi_channel_fork_assign(ppi_channel2, nrf_rtc_task_address_get(rtc.p_reg, NRF_RTC_TASK_CLEAR));
    APP_ERROR_CHECK(err_code);


    // Enable both configured PPI channels
    err_code = nrf_drv_ppi_channel_enable(ppi_channel);
    APP_ERROR_CHECK(err_code);

    	/* Modification */
	err_code = nrf_drv_ppi_channel_enable(ppi_channel2);
    APP_ERROR_CHECK(err_code);
	/* END */
}

/** @brief Function initialization and configuration of RTC driver instance.
 */
static void rtc_config(void)
{
    uint32_t err_code;

    uint32_t compare_val = RTC_US_TO_TICKS(20000UL, RTC_DEFAULT_CONFIG_FREQUENCY);

    uint32_t compare_val2 = RTC_US_TO_TICKS(100000UL, RTC_DEFAULT_CONFIG_FREQUENCY);

    //Initialize RTC instance
    nrf_drv_rtc_config_t config = NRF_DRV_RTC_DEFAULT_CONFIG;
    
#ifdef USE_PPI 
    err_code = nrf_drv_rtc_init(&rtc, &config, NULL);
    APP_ERROR_CHECK(err_code);
    //Set compare channel to trigger interrupt after COMPARE_COUNTERTIME seconds
    err_code = nrf_drv_rtc_cc_set(&rtc,0, compare_val, false);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_rtc_cc_set(&rtc,1, compare_val2, false);
    APP_ERROR_CHECK(err_code);
#else
    err_code = nrf_drv_rtc_init(&rtc, &config, rtc_event_handler);
    APP_ERROR_CHECK(err_code);
    //Set compare channel to trigger interrupt after COMPARE_COUNTERTIME seconds
    err_code = nrf_drv_rtc_cc_set(&rtc,0, compare_val, true);
    APP_ERROR_CHECK(err_code);
#endif
}

/**
 * @brief Function for application main entry.
 */
int main(void)
{
    lfclk_config();
    rtc_config();
#ifdef USE_PPI
    gpiote_config();    
    ppi_init();
#else
    gpio_config();
#endif 
    //Power on RTC instance
    nrf_drv_rtc_enable(&rtc);
    while (true)
    {
        __SEV();
        __WFE();
        __WFE();
    }
}


/**  @} */