How to connect nrf9160 with multiple bme280 sensor?

RE: How to connect nrf9160 with multiple bme280 sensor?

Albrecht Markus Schellenberger — Tue, 27 Apr 2021 07:36:26 GMT

I am using nRF Connect SDK v1.5.1 which includes Zephyr v2.4.99. I recommend you using this version as well.

Regards,

Markus

RE: How to connect nrf9160 with multiple bme280 sensor?

AMG — Mon, 26 Apr 2021 14:48:43 GMT

nRF Connect SDK version along with zephyr. I assume you are using v1.2.0 with zephyr version v.2.1.

Regards,

Ahmed

RE: How to connect nrf9160 with multiple bme280 sensor?

Albrecht Markus Schellenberger — Mon, 26 Apr 2021 13:55:56 GMT

Hello Ahmed,

Do you mean the modem firmware of the nRF9160 or which version of the nRF Connect SDK?

Regards,

Markus

RE: How to connect nrf9160 with multiple bme280 sensor?

AMG — Mon, 26 Apr 2021 12:42:40 GMT

Hi,

What firmware version are you using ?

Kind regards,

-Ahmed

RE: How to connect nrf9160 with multiple bme280 sensor?

Albrecht Markus Schellenberger — Tue, 20 Apr 2021 13:12:52 GMT

As you can see in the memory instantiation, the nRF9160 has four I2C peripherals. Considering the address limitation of the BME280, that means you can connect up to 8 BME280 sensors to it. But then you have to make sure that the other peripherals using the same memory instantiation are disabled, which probably is the reason why CMake didn’t complete.

If you would like to connect more than 8 sensors, you have to switch over to the SPI peripheral or use it in combination with I2C. But even there the number of devices you can communicate with is limited to under 30, depending on the design of the chip select.

Regards,

Markus

RE: How to connect nrf9160 with multiple bme280 sensor?

PoNien Su — Tue, 20 Apr 2021 06:46:33 GMT

Hello Marcus,

Thanks for your answer and it really helps me a lot., but now I meet another problem.

When I followed the steps and trying to create the forth I2C-bus in overlay file, it didn't allow me to complete CMake.

Does it mean that I could only connect 6 bme280 sensors to nrf9160dk? Or is there any solution that can help me to connect up to 30 bme280 sensors to my dk since there are 31 pins on it?

Sorry for bothering again.

Regards,

PoNien Su

RE: How to connect nrf9160 with multiple bme280 sensor?

Albrecht Markus Schellenberger — Mon, 19 Apr 2021 14:09:08 GMT

Hello PoNien Su,

Here is an example of how you can connect three BM280 sensors to the nRF9160 DK using the I2C-interface.

Since the device addresses of the BME280 are limited to 0x76 and 0x77, you can connect two sensors to one I2C-bus and the third to an additional one.

Your overlay file will then look like this:

&i2c2 {
	bme280_76@76 {
		compatible = "bosch,bme280";
		reg = <0x76>;
		label = "BME280_76";
	};
	bme280@77 {
		compatible = "bosch,bme280";
		reg = <0x77>;
		label = "BME280";
	};
};

&i2c3 {
	sda-pin = < 0x12 >;
	scl-pin = < 0x11 >;
	compatible = "nordic,nrf-twim";
	status = "okay";	
	bme280_i2c3@77 {
		compatible = "bosch,bme280";
		reg = <0x77>;
		label = "BME280_I2C3";
	};
};

&spi3 {
	status = "disabled";
};

Be aware that due to memory instantiation, you have to disable the SPI3 interface. See:

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf9160%2Fmemory.html&anchor=topic

Make sure that you are using the following options in prj.conf:

CONFIG_I2C=y
CONFIG_SENSOR=y
CONFIG_BME280=y

You can now use the sensors in main.c in the same way as demonstrated in the tutorial.

I hope this will help you! Let me know if you have any more questions.

Regards,

Markus