There is a low power pwm in nRF5 SDK. I can not find it in the nRF Connect SDK. Any suggestion how to achieve the same using nRF Connect SDK?
There is a low power pwm in nRF5 SDK. I can not find it in the nRF Connect SDK. Any suggestion how to achieve the same using nRF Connect SDK?
Einar Thorsrud unfortunately I need some more support. I am totally new to nRF and Zephyr.
I am using nRF Connect SDK 2.1.2 and the nRF52840 development kit. I have modified the prj.conf file and added CONFIG_PWM_NRF5_SW:
CONFIG_PRINTK=y CONFIG_LOG=y # PWM CONFIG_PWM=y CONFIG_PWM_NRF5_SW=y #CONFIG_PWM_LOG_LEVEL_DBG=y
I have modified the Fade LED Sample to use two PWM channels:
/*
* Copyright (c) 2016 Intel Corporation
* Copyright (c) 2020 Nordic Semiconductor ASA
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file Sample app to demonstrate PWM-based LED fade
*/
#include <zephyr/zephyr.h>
#include <zephyr/sys/printk.h>
#include <zephyr/device.h>
#include <zephyr/drivers/pwm.h>
static const struct pwm_dt_spec pwm_led0 = PWM_DT_SPEC_GET(DT_ALIAS(pwm_led0));
static const struct pwm_dt_spec pwm_led1 = PWM_DT_SPEC_GET(DT_ALIAS(pwm_led1));
#define NUM_STEPS 50U
#define SLEEP_MSEC 1000U
void main(void)
{
uint32_t period = PWM_KHZ(4);
uint32_t pulse_width = period / 2;
//uint32_t pulse_width = 0U;
//uint32_t step = pwm_led1.period / NUM_STEPS;
//uint8_t dir = 1U;
int ret;
bool state = false;
printk("PWM-based LED fade\n");
if (!device_is_ready(pwm_led0.dev)) {
printk("Error: PWM device %s is not ready\n",
pwm_led0.dev->name);
return;
}
if (!device_is_ready(pwm_led1.dev)) {
printk("Error: PWM device %s is not ready\n",
pwm_led1.dev->name);
return;
}
while (1) {
if (state)
{
pulse_width = 0;
state = false;
}
else
{
pulse_width = period / 2;
state = true;
}
ret = pwm_set_dt(&pwm_led0, period, pulse_width);
if (ret) {
printk("Error %d: failed to set pulse width\n", ret);
return;
}
ret = pwm_set_dt(&pwm_led1, period, pulse_width);
if (ret) {
printk("Error %d: failed to set pulse width\n", ret);
return;
}
k_sleep(K_MSEC(SLEEP_MSEC));
}
}
I have added an app.overlay file to modify the Device Tree:
/ {
pwmleds {
compatible = "pwm-leds";
pwm_led0: pwm_led_0 {
pwms = <&sw_pwm 0 PWM_KHZ(4) PWM_POLARITY_INVERTED>;
};
pwm_led1: pwm_led_1 {
pwms = <&sw_pwm 1 PWM_KHZ(4) PWM_POLARITY_NORMAL>;
};
};
aliases {
pwm-led1 = &pwm_led1;
};
};
&sw_pwm {
status ="okay";
channel-gpios = <&gpio0 13 GPIO_ACTIVE_LOW>,
<&gpio0 14 GPIO_ACTIVE_LOW>;
clock-prescaler = <0>;
generator = < &rtc0>;
};
Added the sw_pwm to use the RTC and added the pwm-led information.
The result on the P0.13 and P0.14 is exactly as I have expected:
but in VS Code I get the flowing "error" during the proj.conf edit:
CONFIG_PWM_NRF5_SW was assigned the value y, but got the value n. Missing dependencies:
DT_HAS_NORDIC_NRF_SW_PWM_ENABLED
I have tried to search the GitHub for some cluses: https://github.com/zephyrproject-rtos/zephyr/search?q=DT_HAS_NORDIC_NRF_SW_PWM_ENABLED but I still do not know what I am doing wrong and how to fix the missing dependency on: DT_HAS_NORDIC_NRF_SW_PWM_ENABLED.
Einar Thorsrud thank you very much for taking the time and checking it on your end.
Can you double check that the overlay files are used?
The app.overlay is used - without it I get a build break as the pwm_led1 is undefined.
If they are, then you should see that CONFIG_PWM_NRF5_SW=y in build/zephyr/.config
I see CONFIG_PWM_NRF5_SW=y in build/zephyr/.config:
As you can see I have set CONFIG_PWM_LOG_LEVEL_DBG=y to mimic your settings. I still see the same "error":
At this point I will assume this is a minor issue related to VS Code and how it does the on the fly parsing. I will try to update to nRF Connect SDK 2.2.0 during the weekend and let you know if it changes something.
BTW - is there a way to add an offset between PWM cannel 0 and PWM channel 1? I have seen some discussions how to do in the legacy nRF5 SDK, but I do not know how to do it in Zephyr using nRF Connect SDK.