nRF52840DK SPI Issues

RE: nRF52840DK SPI Issues

Kazi Afroza Sultana — Tue, 02 Dec 2025 11:36:07 GMT

Hello,

The I²C bus requires pull‑up resistors. The nRF internal pulls are disabled by default; you must either:

Use external pull‑ups, or
Enable internal pull‑ups in the pinctrl for the I2C instance.

In our default device tree of nRF52840 internal bias pull up is not enabled. If you don't have external pull up resistor in your design, you have to make it enabled in the device tree.

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

    i2c0_sleep: i2c0_sleep {
        group1 {
            psels = <NRF_PSEL(TWIM_SDA, 0, 27)>,
                    <NRF_PSEL(TWIM_SCL, 0, 26)>;
            low-power-enable;
        };
    };
};

&arduino_i2c {
    status = "okay";
    pinctrl-0 = <&i2c0_default>;
    pinctrl-1 = <&i2c0_sleep>;
    pinctrl-names = "default", "sleep";
};

RE: nRF52840DK SPI Issues

Austinag — Mon, 24 Nov 2025 21:44:40 GMT

Here is the entire driver and sample code I am using. To see the example project with the related overlay navigate to BMP585-I2C-SPI_v1.0.0-beta/zephyr/samples/sensor/bmp585.

To build the project exactly like I have it. just build that sample and make sure the app.overlay file is referenced

devzone.nordicsemi.com/.../BMP585_2D00_I2C_2D00_SPI_5F00_v1.0.0_2D00_beta.zip

RE: nRF52840DK SPI Issues

Austinag — Mon, 24 Nov 2025 21:39:54 GMT

Neither of those pins should be used for NFC as the nRF52840DK has NFC pins on P0.09 & P0.10.

For this test I have nothing connected for this exact reason to make sure nothing is pulled up.

The line I believe you are referencing is:

int-gpios = <&gpio0 3 GPIO_ACTIVE_HIGH>;

This line is used to configure the interrupt pin of the BMP585 device. The I2C pins you are referencing are defined behind the abstraction you mentioned. You can see the actual definitions here.

RE: nRF52840DK SPI Issues

Kazi Afroza Sultana — Mon, 24 Nov 2025 21:35:28 GMT

Hello,

Can you please send me the board file?

RE: nRF52840DK SPI Issues

snoopy20 — Mon, 24 Nov 2025 13:07:19 GMT

Are either of those pins used for the NFC? It's caught me out before - you need to disable with the relevant fuse flag.

Potential daft question is the pin connected to anything - is that driving it low?

I don't know what that config abstraction means but I2C requires pull-ups and disconnected GPIO_HIGH driver. GPIO_ACTIVE_HIGH suggests it's driven high which is wrong?