Basic SPI reads and writes

[RodWatt]

Hi,

I have a SPI peripheral connected to the nRF960 DK. In order to access this correctly, I need to be able to write a byte to a specific address first and then read back from specific addresses. 

I can run the basic SPI example

https://github.com/Rallare/fw-nrfconnect-nrf/tree/nrf9160_samples/samples/nrf9160/spi

which carries out a basic loop back. This all works fine but I can't see how to write a specific byte to a specific address or read a specific address.

So, ideally I would like to write 0xD2 to address 0x80, wait 1 second and then read data from address 0x00.

Can you point me to a simple example please?

Ta,
Rod

[Øyvind]

Hello Rod, 

The SPI example you are using is the only one we have at the moment. The example is using the built-in SPI functions of the Zephyr project, perhaps you are able to find what you are looking for in the Zephyr samples? Also, have a look at the Zephyr SPI API and the SPI header file.

Ref. similar answer given by my colleague Jan Tore here. 

Kind regards,
Øyvind

[RodWatt]

Hi Øyvind,

I went back to the reply from Jan Tore on the ticket here. I realised that the BME280 has both an I2C and an SPI interface. So, I thought if I can get this sensor working over SPI and I can then try and migrate it to my own SPI sensor.

I have successfully connected and ran the BME280 sensor over I2C. I am now trying to access this over SPI. 

Im using the sample given here, 

https://github.com/zephyrproject-rtos/zephyr/blob/master/samples/sensor/bme280/src/main.c

I have set up SPI in my overlay file as suggested by Jan in the other ticket.

/*
 *
 * Copyright (c) 2018 Linaro Limited
 *
 * SPDX-License-Identifier: Apache-2.0
 */


&i2c2 {
        status = "ok";
        sda-pin = <1>;
        scl-pin = <0>;
        clock-frequency = <I2C_BITRATE_FAST>;
        };

&spi3 {
        status = "ok";
	sck-pin = <10>;
	mosi-pin = <11>;
	miso-pin = <12>;
	ss-pin = <13>;
	spi-max-frequency = <8000000>;
	bme280@0 {
		compatible = "bosch,bme280";
		reg = <0>;
		spi-max-frequency = <8000000>;
		label = "BME280";
	};

};

and also I have enabled SPI in my conf file

CONFIG_CONSOLE_SUBSYS=y
CONFIG_CONSOLE_GETCHAR=y
CONFIG_GPIO=y
CONFIG_STDOUT_CONSOLE=y

CONFIG_SERIAL=y
CONFIG_STDOUT_CONSOLE=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_TEST_RANDOM_GENERATOR=y

CONFIG_I2C=y
CONFIG_SENSOR=y

CONFIG_NET_BUF_USER_DATA_SIZE=1

CONFIG_LOG=n
CONFIG_LOG_DEFAULT_LEVEL=4
CONFIG_HEAP_MEM_POOL_SIZE=1024
CONFIG_MAIN_STACK_SIZE=4096
CONFIG_NEWLIB_LIBC=y

# SPI
CONFIG_SPI=y
CONFIG_SPI_3=y
CONFIG_SPI_3_NRF_SPIM=y
CONFIG_BME280=y
CONFIG_SPI_NRFX=y

However, I get an error

Secure Boot: MSP_NS 200216b0

Secure Boot: prepare to jump to Non-Secure image

***** Booting Zephyr OS v1.13.99-ncs1-5561-gde69d2df908f *****

Exception occurred in Secure State

***** HARD FAULT *****

  Fault escalation (see below)

***** BUS FAULT *****

  Precise data bus error

  BFAR Address: 0x50008120

***** Hardware exception *****

Current thread ID = 0x20020154

Faulting instruction address = 0x41f98

Fatal fault in ISR! Spinning...

Any thoughts?

[Øyvind]

Really glad to hear that it solved the issue!

-Øyvind

[RodWatt]

Yes, it solved the SPM issue, but Im now back to the problem of trying to get SPI to work!

[Øyvind]

Ok. Just to get back on the right track again:

• Are you able to run the SPI example without BME280? What problems are you seeing?
• Is the hard fault issue still there?
  • In prj.conf, you must add:
    

    CONFIG_MAIN_STACK_SIZE=4096

Kind regards,
Øyvind

[RodWatt]

Hi,

I managed to get it working !

Thanks,

Rod

[paul_tanner]

Hi Rod,

I'm travelling the same route on nrfConnect SDK 1.4

Like you I got my I2C version working first and then wanted to use SPI.

Any chance you could share your working sample?

I have also posted this https://devzone.nordicsemi.com/f/nordic-q-a/70393/nrf9160-dk-spi-from-bme280-sensor-config-issue - no answer on that so far.

Thx.

Regards, Paul

[RodWatt]

Hi Paul,

I have not looked at this for a while so I can't say 100% that this code is correct, but I have shared it anyway. Let me know if it works and if not, I will do a bit more digging my end.

&spi3 {
        status = "ok";
	sck-pin = <10>;
	mosi-pin = <11>;
	miso-pin = <12>;
	ss-pin = <13>;
	spi-max-frequency = <4000000>;
	bme280@76 {
		compatible = "bosch,bme280";
		reg = <0x76>;
		spi-max-frequency = <4000000>;
		label = "BME280";
	};

};

CONFIG_CONSOLE_SUBSYS=y
CONFIG_CONSOLE_GETCHAR=y
CONFIG_GPIO=y
CONFIG_STDOUT_CONSOLE=y

CONFIG_SERIAL=y
CONFIG_STDOUT_CONSOLE=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_TEST_RANDOM_GENERATOR=y

CONFIG_SENSOR=y

CONFIG_NET_BUF_USER_DATA_SIZE=1

CONFIG_LOG=y
CONFIG_LOG_DEFAULT_LEVEL=4
CONFIG_HEAP_MEM_POOL_SIZE=1024
CONFIG_MAIN_STACK_SIZE=4096
CONFIG_NEWLIB_LIBC=y

# SPI
CONFIG_SPI=y
CONFIG_SPI_3=y
CONFIG_SPI_3_NRF_SPIM=y
CONFIG_BME280=y
CONFIG_SPI_NRFX=y
CONFIG_SENSOR_LOG_LEVEL_WRN=y

CONFIG_TRUSTED_EXECUTION_NONSECURE=y

#include <zephyr.h>
#include <device.h>
#include <sensor.h>
#include <stdio.h>

#undef DT_BOSCH_BME280_BUS_I2C
#define DT_BOSCH_BME280_BUS_SPI

void main(void)
{

int i;
	printf("Boiler Guardian Test Code - BME280 over SPI \n");
	printf(" \n");

	struct device *dev = device_get_binding("BME280");

	printf("dev %p name %s\n", dev, dev->config->name);

	printf("Boiler Guardian Test Code - BME280 - got binding  \n");
	printf(" \n");

	for(i = 1; i < 2; i++) {
		struct sensor_value temp, press, humidity;

		sensor_sample_fetch(dev);
		sensor_channel_get(dev, SENSOR_CHAN_AMBIENT_TEMP, &temp);
		sensor_channel_get(dev, SENSOR_CHAN_PRESS, &press);
		sensor_channel_get(dev, SENSOR_CHAN_HUMIDITY, &humidity);


		printf("Environmental Temperature: %d.%d Degrees Cent. \n", temp.val1, temp.val2);
		printf("Environmental Pressure: %d.%02d Bar \n", press.val1, press.val2);
		printf("Environmental Humidity: %d.%02d per/cent \n", humidity.val1, humidity.val2);


	}
}

[paul_tanner]

Many thanks Rod.

Things have moved on a lot but this was very helpful in getting me unstuck.

With a bit of help from Simon this is now sorted out.

devzone.nordicsemi.com/.../290233

Regards, Paul