Struggling to use SPI with Zephyr

[DunKCubik]

Hi,

    really new to the Zephyr stuff and Nordic micros. I've been through the dev academy training examples and get how to use GPIO and I2C by getting a pointer to a device structure from the dts file.

But I just cannot work out how to do the same for an spi device!

I have used the same method as the GPIO and LED devices but get errors when I try to get a pointer to the spi device struct....

main.c

#include <zephyr/zephyr.h>

#include <drivers/gpio.h>

#include <zephyr/drivers/spi.h>

 struct device *spiDev;  /* SPI device pointer*/

void main(void)

{

    spiDev = DEVICE_DT_GET(DT_NODELABEL(spi0));

}

in the nrf52840dk_nrf52840 dts file spi0 is defined as...

  spi0: spi@40003000 {

                        compatible = "nordic,nrf-spi";

                        #address-cells = <1>;

                        #size-cells = <0>;

                        reg = <0x40003000 0x1000>;

                        interrupts = <3 NRF_DEFAULT_IRQ_PRIORITY>;

                        max-frequency = <DT_FREQ_M(8)>;

                        status = "disabled";

                        pinctrl-0 = <&spi0_default>;

                        pinctrl-1 = <&spi0_sleep>;

                        pinctrl-names = "default", "sleep";

                };

I keep getting this error..

C:\ncs\myApps\MySPI_Example1\src\main.c:15: undefined reference to `__device_dts_ord_105'

All I want to do it control a display device via spi, which I have done on other micros fairly easily in the past, so what am i doing wrong here?

I've looked at lots of the examples, including the spi bitbang one but am really confused!!

Many thanks!

[ovrebekk]

Hi Duncan

You could have a look at an SPI master/slave example I made here. 

I believe the issue in your case is the nodelabel. spi0 is the name of the node from the board definition, you should not use this as the label. 

Rather I would try something like this:

// Overlay
my_spi: spi0 {
  // Add properties here 
};

// Source code
struct device *spiDev;  /* SPI device pointer*/
void main(void)
{
    spiDev = DEVICE_DT_GET(DT_NODELABEL(my_spi));
}

Best regards
Torbjørn

[DunKCubik]

That's great! Thanks for the example, I have managed to get something working after realising that I needed an overlay file! Your example is really good and I understand it much better now. Thank you so much.

[ovrebekk]

Hi Duncan

Thanks for the update, it seems I was using the device_is_ready(..) function incorrectly. Most zephyr functions return an int, but this one returns a bool, so I had to change the example a little. 

If you check out my latest update I have corrected this. 

The overlay warnings I can see here also, but they don't seem to affect the example. I will try to find some time later to look into this. 

Best regards
Torbjørn

[DunKCubik]

Hi ovrebekk,

             thanks for your reply. I'll check out the update later on. Many thanks for your help, I'm up to speed on SPI now!

Duncan

[ovrebekk]

Hi Duncan

Glad I could help. A big thanks to you for pointing out the mistake in the example

Best regards
Torbjørn

[s23]

Hi ovrebekk

Apologies for chiming in on this years later, but I have a question regarding your devicetree overlay for the NRF5340 DK, specifically the code below:

my_spi_master: &spi4 {
	compatible = "nordic,nrf-spim";
	status = "okay";
	pinctrl-0 = <&spi_master_default>;
	pinctrl-1 = <&spi_master_sleep>;
	pinctrl-names = "default", "sleep";
	cs-gpios = <&gpio0 7 GPIO_ACTIVE_LOW>;
	reg_my_spi_master:  spi-dev-a@0 {
		reg = <0>;
	};
};

What does the following code relate to? I cannot find any reference of reg_my_spi_master or spi-dev-a?

Regards

 

[Håkon Alseth]

Hi,

 

This thread is quite old, so if you run into any issues, I highly recommend that you open a new thread.

s23 said:

but I have a question regarding your devicetree overlay for the NRF5340 DK, specifically the code below:

reg-my-spi-master is just a name given to a node under the "my_spi_master" device, which in this case is &spi4.

This is referenced in main.c.

If you look at parts of the nordic dev academy, especially this section on the i2c, you can see a similar approach when implementing a application specific sensor: https://academy.nordicsemi.com/courses/nrf-connect-sdk-fundamentals/lessons/lesson-6-serial-com-i2c/topic/i2c-driver/

 

Kind regards,

Håkon