Fluctuating Idle Current when Using SPI1 (nRF52832)

RE: Fluctuating Idle Current when Using SPI1 (nRF52832)

Crisvin_K — Tue, 09 Dec 2025 17:07:13 GMT

Hello,

Yes, I'll keep this low-power practice in mind for the future.

Thank you,

Crisvin K.

RE: Fluctuating Idle Current when Using SPI1 (nRF52832)

Crisvin_K — Tue, 09 Dec 2025 17:06:34 GMT

Hello hmolesworth,

I appreciate you linking this article.

Thank you!

Crisvin K.

RE: Fluctuating Idle Current when Using SPI1 (nRF52832)

hmolesworth — Tue, 09 Dec 2025 16:58:21 GMT

All GPIO input pins with slow rise/fall or floating inputs exhibit feedthrough leakage when the input happens to float towards the input voltage threshold; this note is from TI but most manufacturers have similar notes:

scba004e

RE: Fluctuating Idle Current when Using SPI1 (nRF52832)

Menon — Tue, 09 Dec 2025 13:31:36 GMT

Hello,

Good to hear that.

[quote user="Crisvin_K"]Is it expected that these pins should be pulled down to minimize current consumption?[/quote]

If you ask me whether it's mandatory, I would say no.However, from a hardware perspective, floating GPIO inputs can cause significant leakage current. So adding pull-downs on SCK/MOSI/MISO is a recommended low-power practice

Kind Regards,

Abhijith

RE: Fluctuating Idle Current when Using SPI1 (nRF52832)

Crisvin_K — Mon, 08 Dec 2025 14:50:58 GMT

Hello,

Thank you for your response. However, I think I found a solution that solves the fluctuating current by making sure SCK, MOSI, and MISO are pulled down while not communicating. Here is how I updated my .overlay file.

// SPI Pin Definitions
	// SCK: nRF Pin 20 -> ANNA-B112 Pin 45
	// MOSI: nRF Pin 19 -> ANNA-B112 Pin 35
	// MISO: nRF Pin 24 -> ANNA-B112 Pin 38
	spi1_default: spi1_default {
		group1 {
			psels = <NRF_PSEL(SPIM_SCK, 0, 20)>,
					<NRF_PSEL(SPIM_MOSI, 0, 19)>,
					<NRF_PSEL(SPIM_MISO, 0, 24)>;
			bias-pull-down;
		};
	};
	spi1_sleep: spi1_sleep {
		group1 {
			psels = <NRF_PSEL(SPIM_SCK, 0, 20)>,
					<NRF_PSEL(SPIM_MOSI, 0, 19)>,
					<NRF_PSEL(SPIM_MISO, 0, 24)>;
			bias-pull-down;
			low-power-enable;
		};
	};

I used the line "bias-pull-down" which ensures that SCK, MOSI, and MISO are not floating. Now the current consumption stays at 4 uA and does not fluctuate when I touch the board or leave it alone for extended periods of time and communication still works correctly.

Is it expected that these pins should be pulled down to minimize current consumption?

Thank you,

Crisvin K.

RE: Fluctuating Idle Current when Using SPI1 (nRF52832)

Menon — Mon, 08 Dec 2025 11:06:39 GMT

Hello,

Which SDK version are you using?

To help narrow down the root cause, please try temporarily disabling the sense-edge-mask in your overlay file. You can either comment out the line or set the mask to 0. This will make the GPIO driver fall back to the default GPIOTE-based interrupt handling instead of the PORT/SENSE workaround.

There is a known anomaly when using GPIOTE for input interrupts, but the extra current from that is only on the order of a few tens of uA much smaller than the ~500 uA jumps you are seeing. So this test is safe and useful for diagnosis.

After removing the sense-edge-mask, please measure the idle current again. If the 4\5 µA to 500 uA fluctuations disappear, then we can confirm that the SENSE-based workaround is contributing to the issue. If the behavior is unchanged, we can rule it out and look elsewhere.

This step will help us isolate whether the interrupt configuration on GPIO0 is causing the unexpected current spikes.

Kind Regards,

Abhijith

RE: Fluctuating Idle Current when Using SPI1 (nRF52832)

Crisvin_K — Tue, 02 Dec 2025 17:05:50 GMT

Hello,

I will also include this video of the behavior I am noticing as well.

devzone.nordicsemi.com/.../1832.Video.mp4

Note that in this video I am not pressing the button SW2, I am just touching the side of the button.