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 ?

[Max_Singsun]

On DK board, use pwm to drive LED3, compare the different bottom current condition between CONFIG_I2C=y and CONFIG_I2C=n

In overlay, config P0.19 to drive LED3:

It seems CONFIG_I2C=y affect power cost of pwm pin ?

[Håkon Alseth]

Hi,

 

Setting CONFIG_I2C=y will cause an added current consumption due to the pins floating.

Try adding a internal pull-up resistor and see if this helps with the current consumption.

 

When running on nRF52-DK, with CONFIG_SERIAL=n, I see this current consumption.

* CONFIG_I2C=n : ~0.3 mA

* CONFIG_I2C=y : ~0.35 mA

* CONFIG_I2C=y + SDA/SCL pin pull up: ~0.3 mA

PS: PWM is active here.

Please note that if I set pwm = 0 % or 100 %, I see < 10 uA.

 

Here's the nrf52dk_nrf52832.overlay file with pull-up on SDA/SCL P0.26/P0.27:

&pinctrl {
	i2c0_default: i2c0_default {
		group1 {
			psels = <NRF_PSEL(TWIM_SDA, 0, 26)>,
				<NRF_PSEL(TWIM_SCL, 0, 27)>;
			bias-pull-up;
		};
	};
};

 

Please note that the I2C is now idle, and if started; you should use the pm_device API to set it to sleep/active state, similar to what is shown here:

https://github.com/nrfconnect/sdk-zephyr/blob/ncs-v3.1.1/samples/sensor/apds9960/src/main.c#L80-L83

   

Kind regards,

Håkon

[Max_Singsun]

Hi Hakon, 

I try your code on my DK board, I found i2c0 is okay, but if I change i2c0 to i2c1,  and use P0.03/P0.04, the issue（bottom current increase） can be reproduce, as below: 

&pinctrl {
    i2c1_default: i2c1_default {  //use i2c1, and P0.03/P0.04
        group1 {
        psels = <NRF_PSEL(TWIM_SDA, 0, 4)>,
        <NRF_PSEL(TWIM_SCL, 0, 3)>;
        bias-pull-up;
        };
    };
};

[Håkon Alseth]

Hi,

 

If the I2C is active, it will raise your current consumption, and you will need to do as I previously shared, ie. turn off the hardware peripheral:

Håkon Alseth said:

Please note that the I2C is now idle, and if started; you should use the pm_device API to set it to sleep/active state, similar to what is shown here:

https://github.com/nrfconnect/sdk-zephyr/blob/ncs-v3.1.1/samples/sensor/apds9960/src/main.c#L80-L83

 And pull-up resistors shall be applied when the I2C is disabled.

 

Can you please try to disable I2C and apply pull-ups to the pins when entering sleep in this scenario?

Max_Singsun said:

2. On product board(P0.26 drive LED), keep I2C pin disconnect, let CONFIG_I2C=n and delete all I2C application code(delete I2C init and other I2C ops), high bottom current disappear(bottom current  is about 5~6 uA).

Kind regards,

Håkon

[Max_Singsun]

Hi Hakon,

I 've got the point:  if replace "i2c1" to "i2c0  in overlay file, then the issue dispeared.  I mean that using i2c1 and P0.03/P0.04 may have some bugs in ncs 3.0.2, if you are not sure, you can try i2c1 and P0.03/P0.04 to confirm if it can work, as:

&pinctrl {
    i2c1_default: i2c1_default {  //use i2c1, and P0.03/P0.04
        group1 {
        psels = <NRF_PSEL(TWIM_SDA, 0, 4)>,
        <NRF_PSEL(TWIM_SCL, 0, 3)>;
        bias-pull-up;
        };
    };
};

I want to know why i2c1 and P0.03/P0.04 cannot work together.

[Håkon Alseth]

Hi,

 

spi1 is enabled by default in the nrf52dk board files:

https://github.com/nrfconnect/sdk-zephyr/blob/main/boards/nordic/nrf52dk/nrf52dk_nrf52832.dts#L189-L190

Could you please try what I previously described?

  

Kind regards,

Håkon