nRF Connect SDK: SPI communication is not working on nRF52840 dev kit

RE: nRF Connect SDK: SPI communication is not working on nRF52840 dev kit

rmcin — Fri, 22 Jan 2021 18:59:16 GMT

Thanks for this example Edvin. I was in the process of trying to get an ADXL372 in spi mode going with an nRF52840 dev kit.

I have not been able to get the chip select working (nrfx_spi.c if p_config->ss_pin set to 0xFF NRFX_SPI_PIN_NOT_USED). So it appears the work around in the sample you showed of using gpio_pin_set() at the main.c level was the only way I good send valid mosi data. The only change would be that I did not OR the SPI_MODE_CP0L bit so the clock goes back low.

I am using nrf connect sdk and building with SES 1.4.99 dev1. I am running the adxl372 sample using this in the overlay. I can get your sample working with the same overlay and prj.config, but when I run the adxl372 example I get no activity on the logic analyzer.

My question is would a sensor driver need to call gpio_pin_set() for the ss pin to function?

&spi1 {
cs-gpios = <&gpio0 16 GPIO_ACTIVE_LOW>;
sck-pin = <31>;
mosi-pin = <30>;
miso-pin = <40>;
adxl372@0 {
compatible = "adi,adxl372";
reg = <0>;
spi-max-frequency = <1000000>;
//spi-max-frequency = <8000000>;
label = "ADXL372";
int1-gpios = <&gpio1 14 GPIO_ACTIVE_HIGH>;
};
};
&spi2 {
status = "disabled";
};

&gpiote {
status = "okay";
};

&gpio0 {
status = "okay";
};

&gpio1 {
status = "okay";
};

prj.conf

CONFIG_STDOUT_CONSOLE=y
CONFIG_LOG=y

CONFIG_GPIO=y
CONFIG_SPI=y
CONFIG_SPI_1=y
CONFIG_SPI_2=n
CONFIG_SPI_NRFX=y
CONFIG_SENSOR=y
CONFIG_ADXL372=y
CONFIG_ADXL372_SPI=y
CONFIG_SENSOR_LOG_LEVEL_WRN=y

CONFIG_CBPRINTF_FP_SUPPORT=y

RE: nRF Connect SDK: SPI communication is not working on nRF52840 dev kit

Kalyan Agepati — Sat, 31 Oct 2020 14:18:40 GMT

Hi Edvin,

Thanks for the quick response and changes.

I have connected CS to GND and now I am receiving the valid data on MOSI.

Regards,

Kalyan

RE: nRF Connect SDK: SPI communication is not working on nRF52840 dev kit

Edvin — Thu, 29 Oct 2020 14:54:01 GMT

Are you sure you didn't change the SPI config?

What happens if you try the following main.c file:

/*
* Copyright (c) 2012-2014 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/

#include <zephyr.h>
#include <sys/printk.h>
#include <drivers/spi.h>
#include <drivers/gpio.h>

#define LED_PIN 16
#define SS_PIN 31

#define TEST_STRING "Southic"

static const struct spi_config spi_cfg = {
	.operation = SPI_OP_MODE_MASTER | SPI_WORD_SET(8) | SPI_TRANSFER_MSB |
		     SPI_MODE_CPOL | SPI_MODE_CPHA,
	.frequency = 4000000,
	.slave = 0,
};

struct device * spi_dev;

static void spi_init(void)
{
	const char* const spiName = "SPI_1";
	spi_dev = device_get_binding(spiName);

	if (spi_dev == NULL) {
		printk("Could not get %s device\n", spiName);
		return;
	}
}

void spi_test_send(void)
{
	int err;
	static u8_t tx_buffer[8] = TEST_STRING;
	static u8_t rx_buffer[8];

	tx_buffer[0] = 0x3f;
	
	for (int i=0; i<sizeof(tx_buffer);i++)
	{
		//tx_buffer[i] = 0x61 + i;
		rx_buffer[i] = 0x00;
	}

	const struct spi_buf tx_buf = {
		.buf = tx_buffer,
		.len = sizeof(tx_buffer)
	};
	const struct spi_buf_set tx = {
		.buffers = &tx_buf,
		.count = 1
	};

	struct spi_buf rx_buf = {
		.buf = rx_buffer,
		.len = sizeof(rx_buffer),
	};
	const struct spi_buf_set rx = {
		.buffers = &rx_buf,
		.count = 1
	};
	
	err = spi_transceive(spi_dev, &spi_cfg, &tx, &rx);
	
	if (err) {
		printk("SPI error: %d\n", err);
	} else {
		/* Connect MISO to MOSI for loopback */
		printk("TX sent: ");
		for (uint8_t i=0; i<6; i++)
		{
			printk("%x", tx_buffer[i]);
		}
		printk("\r\nRX recv: ");
		for (uint8_t i=0; i<6; i++)
		{
			printk("%c", rx_buffer[i]);
		}
		printk("\r\n");
		//tx_buffer[0]++;
	}	
}

void main(void)
{
	int ret;
	bool my_bool = false;

	struct device * dev = device_get_binding("GPIO_0");
	if (!dev) {
		printk("Device not found\n");
		return;
	}
	ret = gpio_pin_configure(dev, LED_PIN, GPIO_OUTPUT_ACTIVE);
	if (ret < 0)
	{
		printk("failed %d", ret);
	}
	ret = gpio_pin_configure(dev, SS_PIN, GPIO_OUTPUT_ACTIVE);
	if (ret <0)
	{
		printk("failed %d", ret);
	}
	printk("SPIM Example\n");
	
	spi_init();
	

	while (1) {
		gpio_pin_set(dev, LED_PIN, my_bool);
		
		my_bool = !my_bool;
		printk("my_bool %d\r\n", my_bool);
		gpio_pin_set(dev, SS_PIN, false);
		spi_test_send();
		gpio_pin_set(dev, SS_PIN, true);
		k_sleep(K_MSEC(1000));
	}
}

(you can remove the LED pin output if you like. I used this for testing, and it prints "?outhic".

Does it do that for you as well? You should see it in the logic analyzer. Try to enable the following settings:

But with your own channels for mosi, miso and clock.

BR,

Edvin

RE: nRF Connect SDK: SPI communication is not working on nRF52840 dev kit

Kalyan Agepati — Wed, 28 Oct 2020 13:58:35 GMT

Hi Edvin,

Thanks for the suggestion. Now I am able to see the proper clock coming on SCK pin but not seeing valid data received on the MOSI pin.

For your information, I have tried to transmit one byte '?' (x3f) data and expected to receive MOSI data signal should be 00111111 but I have received 00101000 which is not correct. Can you please let me know if anything I have missed in the SPI configuration and test code?

Thanks in advance.

Regards,

Kalyan

RE: nRF Connect SDK: SPI communication is not working on nRF52840 dev kit

Edvin — Wed, 28 Oct 2020 10:05:59 GMT

Hello,

Your screenshot says you are sampling at 500kHz, but your SPI is running at 2MHz. Can you please try to sample using a higher sample rate on the logic analyzer?