SPI slave configuration & overlay

[Ubaid_M]

Hi,

I am using BL653 dvk to write an application for SPI,

In my prj.conf, I added below parameters:

CONFIG_SPI=y
CONFIG_SPI_ASYNC=y

Now when I am debugging SPI master code, execution enters the file "spi_nrfx_spi.c", and transfers data & rest is fine.

But when I try to use SPI slave configuration, execution enters the same file "spi_nrfx_spi.c", into the function:

static inline nrf_spi_bit_order_t get_nrf_spi_bit_order(uint16_t operation)
{
	if (operation & SPI_TRANSFER_LSB) {
		return NRF_SPI_BIT_ORDER_LSB_FIRST;
	} else {
		return NRF_SPI_BIT_ORDER_MSB_FIRST;
	}
}

static int configure(const struct device *dev,
		     const struct spi_config *spi_cfg)
{
	struct spi_nrfx_data *dev_data = get_dev_data(dev);
	const struct spi_nrfx_config *dev_config = get_dev_config(dev);
	struct spi_context *ctx = &dev_data->ctx;
	nrfx_spi_config_t config;
	nrfx_err_t result;

	if (dev_data->initialized && spi_context_configured(ctx, spi_cfg)) {
		/* Already configured. No need to do it again. */
		return 0;
	}

	if (SPI_OP_MODE_GET(spi_cfg->operation) != SPI_OP_MODE_MASTER) {
		LOG_ERR("Slave mode is not supported on %s", dev->name);
		return -EINVAL;
	}

& logs an error saying "Slave mode is not supported on".

I understand that I need to make changes to prj.conf &  also write an overlay file for bl653.

1. But I do not know how to write overlay for this case, I am using SPI_1 and wrote an overlay as:

&spi1 {
	compatible = "nordic,nrf-spis";
	status = "okay";
	sck-pin = <41>;
	mosi-pin = <40>;
	miso-pin = <4>;
	cs-gpios = <&gpio1 23 0>;
};

But is still not working,

2. Kindly also help me on what changes to be done in prj.conf to have SPI_0 in slave mode.



Thanks,

[Sigurd]

Ubaid_M said:

1. what do csn-pin & def-char attributes do..?

Here is the documentation for these attributes:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.8.0/zephyr/reference/devicetree/bindings/spi/nordic,nrf-spis.html

https://github.com/nrfconnect/sdk-zephyr/blob/v2.7.0-ncs1/dts/bindings/spi/nordic,nrf-spis.yaml

Ubaid_M said:

so is my definition right..?

Looks correct

[Ubaid_M]

Hello Sigurd,

Thanks for the kind help,

Now the code execution is on track on bl653 running spi slave driver.

But the spi_read always returns -116, that is  -ETIMEDOUT.

But I do not understand why slave driver always returns -ETIMEDOUT. Master board is sending data, i checked on USB logic analyzer for the same.

I traced the flow of execution all the way to the source of the error and here is what I found

spi_read( ) -> transceive (in file "spi_nrfx_spis.c") -> spi_context_wait_for_completion( in file "spi_context.h") -> and the source of error is as attached in the below snap in #else part

Without debug mode as well I am getting the same -ETIMEDOUT.

Kindly suggest on if I have missed out on configuring something.

adding my overlay file details for your reference:

&spi1 {
	compatible = "nordic,nrf-spis";
	status = "okay";
	sck-pin = <41>;
	mosi-pin = <40>;
	miso-pin = <4>;
	cs-gpios = <&gpio1 23 0>;
	csn-pin = <23>;
	def-char = <0xFF>;
};

Kindly suggest

[Sigurd]

This new issue will be handled in this new case: https://devzone.nordicsemi.com/f/nordic-q-a/83583/spi-slave-always-returns--etimedout

Closing this case.