Why 'pwm_set_dt(xxx, 0)' can not set gpio floating on NCS SDK 3.0.2 ？

[Max_Singsun]

For power cost down, use dts config  to set pwm gpio H0D1 as follow:

pwm1_default: pwm1_default {
group1 {
psels = <NRF_PSEL(PWM_OUT1, 0, 26)>;
nordic,drive-mode = <NRF_DRIVE_H0D1>;
};
};

1. When on NCS 2.4.1,  pwm func 'pwm_set_dt(xxx, 0)' can set gpio floating

2. When on NCS 3.0.2, 'pwm_set_dt(xxx, 0)' can NOT set gpio floating, because current get up 50 uA !

How can I use  'pwm_set_dt(xxx, 0)' set pwm gpio floating ?  and get current cost down?

[Håkon Alseth]

Hi,

 

The code will, in ncs v3.0.2, set the GPIO as output high or low, if the duty cycle is either 100 % or 0 %.

If you are seeing 50 uA higher consumption than expected, it sounds like it is not the PWM itself that is causing this.

 

Kind regards,

Håkon

[Max_Singsun]

I find the key !

Now I use demo ''v3.0.2\zephyr\samples\basic\blinky_pwm" to test the problem.  I found that if add CONFIG_I2C=y to the demo, the current cost will increase about 50uA, and if I let CONFIG_I2C=n, then the current down to normal. Could u explain the phenomenon and tell me how to get it ?

[Håkon Alseth]

Hi,

 

What is the expected current, and what is the total measured current. I understand that the difference is 50 uA, but what is the overall target?

 

Max_Singsun said:

Could u explain the phenomenon and tell me how to get it ?

I will need more information about which pins you're using, and what state you place SDA/SCL in active/non-active mode.

 

Kind regards,

Håkon

[Max_Singsun]

SDA/SCL is unused, just let CONFIG_I2C=y, No any operations on I2C interface. 

50 uA are get on product board, but I try it on DK board, original test data is 15 uA, but let CONFIG_I2C=y, the current is up to 170uA as most as I see.

by the way: config P0.19 as pwm output pin on DK in blinky_pwm

[Håkon Alseth]

Hi,

 

I would recommend that you set your connected GPIOs in a idle state, as it sounds like there are signals that are floating on your board.

Is this a custom board? Please check connections to external sensors, and ensure that the connected sensors are idle, by for instance having pull-up on the SDA/SCL lines.

 

Kind regards,

Håkon

[Max_Singsun]

First, I test on DK board finally, except for the LED which uses P0.19, no other GPIO is used, no external sensors