SDA and SCL pins not as defined in overlay file in nRF9160DK.

Question

Hi, I'm trying to connect an external I2C device to the nrf9160DK and read some registers. I'm using NCS v1.9.1.

I have my file nrf9160dk_nrf9160_ns.overlay defined like this

&i2c1 {
    compatible = "nordic,nrf-twim";
    status = "okay";
    sda-pin = <30>;
    scl-pin = <31>;
    clock-frequency = <I2C_BITRATE_STANDARD>;
};

To see if the I2C bus is beeing initialize correctly I created my main function as

#define I2C_DEV DT_LABEL(DT_NODELABEL(i2c1))
void main(void) {
    const struct device *i2c_dev;

    uint8_t data[16];
    int i, ret;
    struct i2c_msg msg;

    i2c_dev = device_get_binding(I2C_DEV);

    if (!i2c_dev) {
        printk("I2C: Device driver not found.\n");
        return;
    }
    uint8_t error = 0u;

    i2c_configure(i2c_dev, I2C_SPEED_SET(I2C_SPEED_STANDARD));
    printk("Value of NRF_TWIM1_NS->PSEL.SCL: %ld \n", NRF_TWIM1_NS->PSEL.SCL);
    printk("Value of NRF_TWIM1_NS->PSEL.SDA: %ld \n", NRF_TWIM1_NS->PSEL.SDA);
    printk("Value of NRF_TWIM1_NS->FREQUENCY: %ld \n", NRF_TWIM1_NS->FREQUENCY);
    printk("26738688 -> 100k\n");

}

In the PSEL.SCL and PSEL.SDA prints I should be seeing 31 & 30, is that correct?

What I am actuallly seeing is:

Value of NRF_TWIM1_NS->PSEL.SCL: 14
Value of NRF_TWIM1_NS->PSEL.SDA: 1
Value of NRF_TWIM1_NS->FREQUENCY: 26738688
26738688 -> 100k

Do I need to add other configuration steps?

Eneko · Accepted Answer

Hi, I kept investigating and came accross this other post https://devzone.nordicsemi.com/f/nordic-q-a/87823/stuck-at-spm-prepare-to-jump-to-non-secure-image-nrf9160/367672#367672 
 
 His solution, changing to i2c2 worked for me too, now I can see that the PSEL.SCL and PSEL.SDA printed are correct. Furthermore I can scan the I2C bus and find my sensor. 
 
 I don't know why i2c1 is not working but with i2c2 it works correctly.

SDA and SCL pins not as defined in overlay file in nRF9160DK.

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