High current problem for app_pwm SDK13.0

[George Leung]

Hi,

I am working on nRF52832 with SDK13.0 + GCC Eclipse.

I have used 2 app_pwm instances for driving a 3 color led. Once I init the pwm and set the duty cycle, the current increase from 3uA (sleep state) to 6.5mA. This 6.5mA current is just for the MCU as I have a separate power supply for the LED, the MCU is sinking current from the LED. When I call app_pwm_disable and app_pwm_uninit, the current still keep at 6.5mA.

Further more, if I just init the pwm but not set the duty cycle, it would be just 1mA and able to go back to 3uA sleep when I disable the pwm.

I have searched for some post about the pwm which mention about the pan73_workaround fix but I already found that in app_pwm_disable.

I have 2 questions: Is 6.5mA normal for using app_pwm? How to remove that 6.5mA when I disable the pwm?

Regards, George

[George Leung]

Attached some part of the code for your reference:

void pwm_open(void) {
ret_code_t UNUSED err_code;

/* 2-channel PWM, 200Hz, output on DK LED pins. */
app_pwm_config_t pwm1_cfg = APP_PWM_DEFAULT_CONFIG_2CH(5000L, LED_1, LED_2);
app_pwm_config_t pwm2_cfg = APP_PWM_DEFAULT_CONFIG_1CH(5000L, LED_3);

/* Switch the polarity of the second channel. */
pwm1_cfg.pin_polarity[0] = APP_PWM_POLARITY_ACTIVE_LOW;
pwm1_cfg.pin_polarity[1] = APP_PWM_POLARITY_ACTIVE_LOW;
pwm2_cfg.pin_polarity[0] = APP_PWM_POLARITY_ACTIVE_LOW;

/* Initialize and enable PWM. */
err_code = app_pwm_init(&PWM_1, &pwm1_cfg, NULL);
PWM_TRACE("PWM 1 init %d\n", err_code);
err_code = app_pwm_init(&PWM_2, &pwm2_cfg, NULL);
PWM_TRACE("PWM 2 init %d\n", err_code);

app_pwm_enable(&PWM_1);
app_pwm_enable(&PWM_2);

pwm_set_all_channels(0, 0, 0);

}

void pwm_close(void) {
app_pwm_disable(&PWM_1);
app_pwm_disable(&PWM_2);
app_pwm_uninit(&PWM_1);
app_pwm_uninit(&PWM_2);

}

void pwm_set(uint8_t channel, uint16_t duty_cycle) {
float duty_as_frac = duty_cycle / DUTY_MAX;

switch(channel) {
    default:
    case 0:
        duty_cycle = (uint16_t)(RED_SCALE * duty_as_frac * app_pwm_cycle_ticks_get(&PWM_1));
        while(app_pwm_channel_duty_ticks_set(&PWM_1, 0, duty_cycle) == NRF_ERROR_BUSY);
        break;
    case 1:
        duty_cycle = (uint16_t)(GREEN_SCALE * duty_as_frac * app_pwm_cycle_ticks_get(&PWM_1));
        while(app_pwm_channel_duty_ticks_set(&PWM_1, 1, duty_cycle) == NRF_ERROR_BUSY);
        break;
    case 2:
        duty_cycle = (uint16_t)(BLUE_SCALE * duty_as_frac * app_pwm_cycle_ticks_get(&PWM_2));
        while(app_pwm_channel_duty_ticks_set(&PWM_2, 0, duty_cycle) == NRF_ERROR_BUSY);
        break;
}

}