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configuring_env_sensor.md

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Configuring the BME680 Environmetal Sensor

  1. Connect in the five-pin USB cable to the environmental sensor with the black wire connected to the ground pin. env sensor 1

  2. With the device powered off, connect the other end of the five-pin USB cable into the pins shown in the images below of your specific device. Please make sure and take note of which color wire is connected to which pin.

NVIDIA Jetson AGX Orin

Pins on Board Image

reComputer J4012

Pins on Board Image

Raspberry Pi

Pins on Board Image

  1. Run this command to see if the sensor is being detected by i2c. i2cdetect -y -r 7 0x76 0x77

    waggle@wd-nanocore-000048B02D5BFE58:~# i2cdetect -y -r 7 0x76 0x77
    0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                                                 
10:                                                 
20:                                                 
30:                                                 
40:                                                 
50:                                                 
60:                                                 
70:                   76 --

Note: The sensor can either be on 0x76 or 0x77. Based on what address it's on the number will change in the documentation

  1. The kernel supplied by nvidia doesn't support the BME680 sensor, so we just have to get the kernel source of a kernel version supporting the sensor (5.15.148) wget https://www.kernel.org/pub/linux/kernel/v5.x/linux-5.15.148.tar.gz

  2. Extract the drivers/iio/chemical subtree of the kernel source for building the bme680 sensors kernel module tar -xvf linux-5.15.148.tar.gz

  3. After extracting, we have to configure the build. To do so, prepend the following lines to the Makefile in using the following command:

    cd linux-5.15.148/drivers/iio/chemical

# avoid duplicates if you already added them
grep -q '^CONFIG_BME680=m$' Makefile || \
( printf "CONFIG_BME680=m\nCONFIG_BME680_I2C=m\n" ; cat Makefile ) > Makefile.new && mv Makefile.new Makefile

# verify
head -n 5 Makefile

  4. This line is only to be ran on seeed studio orin. This command creates a symbolic link (a shortcut) to the kernel headers. The command points the standard kernel build location (/lib/modules/$(uname -r)/build) to the specific location where the kernel source files are stored on this device.

    sudo ln -sfT /usr/src/linux-headers-5.15.148-tegra-ubuntu22.04_aarch64/3rdparty/canonical/linux-jammy/kernel-source /lib/modules/$(uname -r)/build

  5. Afterwards build the kernel module and install the binaries to the modules folder by running the following commands:

    1. make -C /lib/modules/$(uname -r)/build M=$PWD

    2. sudo make -C /lib/modules/$(uname -r)/build M=$PWD modules_install

    3. If you get the error Warning: modules_install: missing 'System.map' file. Skipping depmod.. Run the following command to make sure the files are present: ls -l /lib/modules/$(uname -r)/updates/bme680*.ko. Once ran you should get an output similar to the one below which confirms that you have installed the module properly.

      -rw-r--r-- 1 root root 86168 Oct  7 17:34 /lib/modules/5.15.148-tegra/updates/bme680_core.ko
-rw-r--r-- 1 root root 54488 Oct  7 17:34 /lib/modules/5.15.148-tegra/updates/bme680_i2c.ko

  6. Build the module's dependency list by running the command depmod -a

  7. Run command modprobe bme680_i2c to see if the module was successfully installed

Note: If there is no output then the module was installed correctly

  1. To use the sensor we have to register it with the kernels i2c subsystem so run this command echo bme680 0x76 | sudo tee /sys/bus/i2c/devices/i2c-7/new_device. Output should look something like this: 
    bme680 0x76

Note: change number to 77 if that's the address the sensor is on

  1. Check if the BME680 sensor is registered by running the command cat /sys/bus/iio/devices/*/name

    waggle@<id>:~# cat /sys/bus/iio/devices/*/name

ina3221x
bme680

  2. Once the sensor is registered, the sensors readings can be acquired using the sysfs interface, run the command grep ^ /sys/bus/i2cxdevices/i2c-7/*-0076/iio:device*/in_*_input:

    waggle@<id>:~#  grep ^ /dev/null /sys/bus/i2c/devices/i2c-7/1-0076/iio:device1/*input*

/sys/bus/i2c/devices/i2c-7/1-0076/iio:device1/in_humidityrelative_input:63.827000000
/sys/bus/i2c/devices/i2c-7/1-0076/iio:device1/in_pressure_input:984.630000000
/sys/bus/i2c/devices/i2c-7/1-0076/iio:device1/in_resistance_input:7234
/sys/bus/i2c/devices/i2c-7/1-0076/iio:device1/in_temp_input:24510

Note: If your sensor is on 0x77 the relative path will be /sys/bus/i2c/devices/i2c-7/1-0077/iio:device1/*input*

  1. If your outputs in steps 11 & 12 are similar then configure the nano to set bme680 on boot

    1. To load the bme680_i2c kernel module on startup add it to the modules.conf file by running this command echo bme680_i2c >> /etc/modules-load.d/modules.conf. Output should be as seen below:

      1. If you get an error running that command run this one instead echo bme680_i2c | sudo tee -a /etc/modules-load.d/modules.conf.
      bme680_i2c

    2. Next, we have to register the sensor with the kernels i2c subsystem on startup. To do so we have to create a rc.local file since ubuntu 18.04 doesn't have it by default. vim /etc/rc.local

      1. Go into insert mode, and paste the following content

        #!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

# Add bme680 to i2c
echo bme680 0x76 > /sys/bus/i2c/devices/i2c-7/new_device

exit 0

      2. Escape insert mode, save and quit file

      3. Give execution permission to the file chmod +x /etc/rc.local

  2. Reboot and on startup run steps 11 & 12 again to see if the BME680 sensor is set up on boot

Continue to the Waggle docs or the Optional Tests to run