PWM current / power consumption

[FormerMember]

Hello,

I need help,

I'am using uvision V5.17, SDK 9.0.0 and SD130.

First problem is solved,

If I don't declare app_pwm_init() in app_pwm.h, the current is 0.4mAh steadily,

but If I declare app_pwm_init() the current increase to 1.6mAh.

So I reference from this blog I found the answer.

but it's not perfect.

static void start_servo(void)
{				
    nrf_drv_gpiote_out_task_enable(SERVO_PIN);

    /* Initialize and enable PWM. */
    uint32_t err_code = app_pwm_init(m_pwm_t, m_pwm1_cfg, servo_ready_callback);
    APP_ERROR_CHECK(err_code);

    app_pwm_enable(m_pwm_t);
}

-----------------------------after above start_servo() the current becomes 1.6mAh

static void stop_servo(void)
{	
	app_pwm_disable(m_pwm_t);
	nrf_drv_gpiote_out_task_disable(SERVO_PIN);

	uint32_t err_code = app_pwm_uninit(m_pwm_t);
	APP_ERROR_CHECK(err_code);

	nrf_gpio_cfg_output(SERVO_PIN);
	nrf_gpio_pin_set(SERVO_PIN);		
}

-----------------------------after above stop_servo() the current becomes 0.3 to 0.9mAh

The problem is that before I declare start_servo() first time,

the current maintain 0.4mAh steadily, but after start_servo() and stop_servo(),

the current maintain 0.3mAh to 0.9mAh rapidly.

I wanna get 0.4mAh or less when I don't use servo. How can I fix it?

[Ole Bauck]

The SDK 9 driver has some known issues regarding app_pwm_uninit() and app_pwm_disable(). I will therefore suggest that you use the SDK 10 driver. You only need to call app_pwm_disable(), as this will stop the timer and reduce the current consumption. app_pwm_uninit() is for deallocate the resources used by the pwm and are therefore not necessary to call in your case. You should also remove the nrf_drv_gpiote calls, this is fixed by the driver. Doing nrf_drv_gpiote calls on the pwm pin may create issues with the pwm driver.

If you don't want to migrate the project to SDK 10, it should be possible to only include the app_pwm.c and app_pwm.h files.

[FormerMember]

I did it as you mentioned that including app_pwm.c and app_pwm.h files from sdk 10. Therefore I only use app_pwm_disable(), but the current still in instability 0.4mAh to 0.8mAh.

It can't be fixed for now?

[Ole Bauck]

What other things are you running? Could you try to only run the PWM part and see if the current is still the same? Are you running multiple instances of PWM?

The PWM driver will require the high frequency clock to run, which will cause an increase in current consumption. The high frequency clock will only be stopped if no resources are requiring it. If you have to PWM instances enabled, then disabling one of them will not decrease the current consumption since the high frequency clock is still running.

[hawk]

i make pwm by setting gpio high or low， and test the current and found the current sometime is not still。 can i disable ble ？

[Ole Bauck]

You can comment out ble_advertising_start(..);, then the device will not start advertising and the current should be more or less stable.