How to access multiple SPI sensors

[cbraissant]

Dear all,

It's my first project with a Nordic chip and with Zepyhr as well, so a little overwhelmed.

I made a PCB based on a nRF52840 and the reference design.
The custom board has been added to my project and tested with various samples.  Everything works on the hardware side.

Now, the tricky part:
The board has 11 similar sensors connected on the same SPI.
The sensors are the ST LPS27HH, but I use the LPS22HH drivers as they are similar.

I can easily access a single sensor on the SPI with:

const struct device *const sensor = DEVICE_DT_GET_ONE(st_lps22hh);

My issue arises when I need to access my sensors from the source code.
I tried multiple different version, but cannot find a loop or a macro equivalent to:

static const struct device *sensors[NUM_SENSORS];

sensors[0] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_0));
sensors[1] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_1));
sensors[2] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_2));
sensors[3] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_3));
sensors[4] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_4));
sensors[5] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_5));
sensors[6] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_6));
sensors[7] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_7));
sensors[8] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_8));
sensors[9] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_9));
sensors[10] = DEVICE_DT_GET(DT_NODELABEL(lps27hh_10));

I tried multiple version, like:

static const struct device *sensors[NUM_SENSORS];
for (int i=0; i<NUM_SENSORS; i++) {
sensors[i] = DEVICE_DT_DEFINE(DT_NODELABEL(lps27hh_ ## i))
}

(In that case, the index i of the loop is not compute by the macro)

Or something like that, with the same issue:

#define MYDEV(idx) DT_NODELABEL(lps27hh_ ## idx)
static const struct device *sensors[NUM_SENSORS];
for (int i=0; i<NUM_SENSORS; i++) {
sensors[i] = DEVICE_DT_DEFINE(MYDEV(i));
}

If you have any idea how to access all my sensor in a better way, I would really appreciate.

Thanks a lot!


PS: Here is my overlay file:

spi0: &spi0 {
status = "okay";
compatible = "nordic,nrf-spim";
pinctrl-0 = <&spi0_default>;
pinctrl-1 = <&spi0_sleep>;
pinctrl-names = "default", "sleep";
max-frequency = <DT_FREQ_M(8)>;

// chip select GPIOs selected by the "reg" property of the slave node.
cs-gpios = <&gpio0 20 GPIO_ACTIVE_LOW>,
<&gpio0 22 GPIO_ACTIVE_LOW>,
<&gpio0 24 GPIO_ACTIVE_LOW>,
<&gpio1 0 GPIO_ACTIVE_LOW>,
<&gpio1 1 GPIO_ACTIVE_LOW>,
<&gpio1 2 GPIO_ACTIVE_LOW>,
<&gpio1 4 GPIO_ACTIVE_LOW>,
<&gpio1 6 GPIO_ACTIVE_LOW>,
<&gpio1 7 GPIO_ACTIVE_LOW>,
<&gpio0 9 GPIO_ACTIVE_LOW>,
<&gpio0 10 GPIO_ACTIVE_LOW>;

lps27hh_0: lps27hh@0 {
compatible = "st,lps22hh";
reg = <0x00>; // address is a chip select line number;
spi-max-frequency = <4000000>;
odr = <7>;
};

lps27hh_1: lps27hh@1 {
compatible = "st,lps22hh";
reg = <0x01>;
spi-max-frequency = <8000000>;
odr = <7>;
};

// More sensors here

lps27hh_10: lps27hh@A {
compatible = "st,lps22hh";
reg = <0x0A>;
spi-max-frequency = <8000000>;
odr = <7>;
};

};

[Simonr]

Hi,

Reuven has a good suggestion here. Additionally, I'd recommend making sure that you have set the pins P0.09 and P0.10 as regular GPIOs by using devicetree to configure NFCT pins as GPIOS like this: &uicr { nfct-pins-as-gpios; };

I see you're using these as GPIOs in your overlay file.

Best regards,

Simon

[cbraissant]

Hi Simon,

Thanks for that recommendation.
I actually had some issue with 2 sensors, and that solved the issue.