nRF9160 with BME280 sensor

RE: nRF9160 with BME280 sensor

Jan Tore Guggedal — Tue, 21 Apr 2020 11:36:27 GMT

"Could not get BME280 device" is usually caused by failure to read the hardware ID from the device in the driver's initialization. Did you get any usueful information from the added logging? Note that CONFIG_LOG=y needs to be set to enable logging system, though there should have been some warnings during compilation if it wasn't on. Hopefully the logs can shed some light on what goes wrong.

In the BME280 datasheet rev 1.6, there's a figuer on page 39 that might be useful to confirm that the hardware setup is correct for I2C operation, especially the CSB and SDO connections. I'd use the default address if there's not an important reason to do otherwise to reduce what can go wrong.

If you're using nRF91 DK, please be aware that it is operating by default at 1.8 V. You can se SW11 next to the power switch to confirm the setting. V_DDIO needs to match the setting, and I'd typically set V_DD to the same. CSB and SDO should be set with GND or V_DDIO.

Regards,

Jan Tore

RE: nRF9160 with BME280 sensor

AMG — Tue, 21 Apr 2020 10:09:59 GMT

V_DDIO is a different voltage from the Vin if so... I connected the CSB to a seprate VDD and SDO to vin and changed the reg to 77 and bme280@77 and got "Could not get BME280 device". Is V_DDIO is just any voltage pin or there is a specific pin on the board. SO now the VCC>>Vin and csb >> VDD.

RE: nRF9160 with BME280 sensor

Jan Tore Guggedal — Tue, 21 Apr 2020 09:55:30 GMT

I see now that I hade a typo in my previous answer about the connections (corrected now).
I intended to write that CSB should be connected to V_DDIO when using I2C. I mixed it up with DS in my first sentence.

Sorry about that.

Jan Tore

RE: nRF9160 with BME280 sensor

Jan Tore Guggedal — Tue, 21 Apr 2020 09:50:10 GMT

Hi,

It would be good with some more logging to better understand what's going on.
You can do that by adding these to your prj.conf:

CONFIG_SENSOR_LOG_LEVEL_DBG=y

CONFIG_CONFIG_I2C_LOG_LEVEL_DBG=y

If the app hangs for some reason, it can also be useful to add
CONFIG_LOG_IMMEDIATE=y

And by the way, did you change both occurences of 0x76 in the overlay to match your hardware configuration? Also bme280@76 needs to be changed.

Cheers
Jan Tore

RE: nRF9160 with BME280 sensor

AMG — Tue, 21 Apr 2020 09:40:03 GMT

even after changing the reg it's the same problem. From what I understood the SDO a weak pull-down resistor on the module pulls SDO low so 0x76 is the default address if the SDO pin is not connected. Connect the SDO to Vcc to select 0x77 but both give the same result (error)

RE: nRF9160 with BME280 sensor

Jan Tore Guggedal — Tue, 21 Apr 2020 09:26:46 GMT

Hi,

From the BME280 datasheet it looks like CSB should be connected to V_DDIO when running in I2C mode. SDO should be grounded to use the default I2C, or V_DDIO if you need to use the alternative one. If you don't want to use the default address (0x76), you need to specify that in the overlay file by changing 0x76 to 0x77.

Best regards,

Jan Tore

RE: nRF9160 with BME280 sensor

AMG — Tue, 21 Apr 2020 09:14:27 GMT

I was able to build after re-naming but after connecting and flashing the sensor doesn't show the values. My connection is as follows SCL >> p0.11 , SDA >> p0.12 , VCC with vin 3-5v , GND >> GND , CSB >> GND , SD >> vin

RE: nRF9160 with BME280 sensor

Jan Tore Guggedal — Mon, 20 Apr 2020 15:24:05 GMT

Hi,

It looks like the issue is that your device tree overlay file name doesn't match your build target.
If you rename it to "nrf9160_pca10090ns.overlay", it should build.

Side note: You'll need to connect the sensor to make your application run paste the "if (dev == NULL)" check.

Best regards,

Jan Tore