Enabling an Off-Board Sensor in an Existing Application¶
This tutorial shows you how to enable an existing application to run on a device with an off-board sensor device connected to it. It allows you to quickly bring up and run a Mynewt application on a device to view sensor data from a sensor device.
We use the sensors_test application running on an nRF52-DK board to
communicate, via the I2C interface, with the Adafruit
sensor. The sensors_test application is a sample application that
demonstrates all the features of the Mynewt sensor framework. The
application includes the sensor framework
sensor shell command that
allows you to view the sensors and sensor data managed by the sensor
framework, and the
bno055 shell command that allows you to control
and query the BNO055 device and to view the sensor data.
This tutorial shows you how to:
Create and build the application and bootloader targets.
Connect a BNO055 sensor device to an nRF52-DK board.
bno055shell commands to view the sensor data and control the bno055 sensor device.
The sensors_test application includes all the packages, and sets the
syscfg settings to values, that are required to enable the full set of
sensor framework features. This tutorial uses a subset of the
sensors_test application functionality because the objective of the
tutorial is to show you how to quickly bring up the sensors_test
application and use the
bno055 shell commands to view
the sensor data from the BNO055 sensor. The instructions in this
tutorial show the syscfg settings that must be enabled in the
sensors_test application to demonstrate the examples shown. The
instructions do not explicity exclude the packages or change the syscfg
setting values to disable the functionality that is not used in the
For your reference, we describe the packages and the setting values that enable the application functionality that this tutorial demonstrates:
hw/sensor: The sensor framework package. This package defines the
SENSOR_CLIsetting that specifies whether the
sensorshell command is enabled. This setting is enabled by default.
hw/sensor/creator: The sensor creator package. This package supports off-board sensor devices. This package creates the os devices in the kernel for the sensors and configures the sensor devices with default values. It defines a syscfg setting for each sensor device and uses the naming convention
<SENSORNAME>_OFB. For example, the syscfg setting for the BNO055 sensor is
<SENSORNAME>_OFBsetting specifies whether the sensor named SENSORNAME is enabled. The setting is disabled by default. This package includes the sensor device driver package
hw/drivers/sensors/<sensorname>and creates and configures a sensor named SENSORNAME when the
SENSORNAME_OFBsetting is enabled by the application.
hw/drivers/sensors/bno055: The driver package for the BNO055 sensor. The creator package adds this package as a package dependency when the
BNO055_OFBsetting is enabled. The driver package defines the
BNO055_CLIsetting that specfies whether the
bno055shell command is enabled. This setting is disabled by default and is enabled by the application. The package also exports the
bno055_shell_init()function that an application calls to initialize the driver shell support.
Note: All sensor driver packages that support a sensor shell command define a syscfg setting to specify whether the shell command is enabled. They also export a shell initialization function that an application must call. The naming convention is
<SENSORNAME>_CLIfor the syscfg setting and
<sensorname>_shell_init()for the initialization function.
sys/shell and sys/console/full: The shell and console packages for shell support over the console. The
SHELL_TASKsetting needs to be set to enable the shell support in the package. The sensors_test application enables this setting by default.
In this step, you create a target for the sensors_test application that enables the BNO055 off-board sensor.
To add the BNO055 sensor support, you create the application target with the following syscfg settings enabled:
I2C_0: Enables the I2C interface 0 in the nRF52 BSP HAL setting.
BNO055_OFB: Enables support for the BNO055 sensor in the sensor creator package (
hw/sensor/creator).When this setting is enabled, the creator package performs the following:
Includes the BNO055 driver package (
hw/drivers/sensors/bno055) as a package dependency.
Creates an os device for the sensor in the Mynewt kernel.
Configures the sensor device with default values.
BNO055_CLI: Enables the
bno055shell command in the bno055 device driver package. The sensors_test application also uses this setting to conditionally include the call to the
bno055_shell_init()function to initialize the shell support in the driver.
Note: This tutorial uses the
sensor and the
SENSOR_CLI setting, that specifies whether the
sensor shell command is enabled, is enabled by default.
1. Run the
newt target create command, from your project base
directory, to create the target. We name the target
$ newt target create nrf52_bno055_test Target targets/nrf52_bno055_test successfully created $
2. Run the
newt target set command to set the app, bsp, and
build_profile variables for the target:
$ newt target set nrf52_bno055_test app=@apache-mynewt-core/apps/sensors_test bsp=@apache-mynewt-core/hw/bsp/nrf52dk build_profile=debug Target targets/nrf52_bno055_test successfully set target.app to @apache-mynewt-core/apps/sensors_test Target targets/nrf52_bno055_test successfully set target.bsp to @apache-mynewt-core/hw/bsp/nrf52dk Target targets/nrf52_bno055_test successfully set target.build_profile to debug $
3. Run the
newt target set command to enable the
BBNO055_CLI syscfg settings:
$ newt target set nrf52_bno055_test syscfg=BNO055_OFB=1:I2C_0=1:BNO055_CLI=1 Target targets/nrf52_bno055_test successfully set target.syscfg to BNO055_OFB=1:I2C_0=1:BNO055_CLI=1 $
Run the following
newt target commands, from your project directory, to create a
bootloader target. We name the target
$ newt target create nrf52_boot Target targets/nrf52_boot successfully created $ newt target set nrf52_boot app=@mcuboot/boot/mynewt bsp=@apache-mynewt-core/hw/bsp/nrf52dk build_profile=optimized Target targets/nrf52_boot successfully set target.app to @mcuboot/boot/mynewt Target targets/nrf52_boot successfully set target.bsp to @apache-mynewt-core/hw/bsp/nrf52dk Target targets/nrf52_boot successfully set target.build_profile to optimized $
newt build nrf52_bootcommand to build the bootloader:
$ newt build nrf52_boot Building target targets/nrf52_boot Compiling repos/mcuboot/boot/bootutil/src/image_ec.c Compiling repos/mcuboot/boot/bootutil/src/image_rsa.c Compiling repos/mcuboot/boot/bootutil/src/image_ec256.c Compiling repos/mcuboot/boot/bootutil/src/loader.c Compiling repos/mcuboot/boot/bootutil/src/bootutil_misc.c Compiling repos/mcuboot/boot/mynewt/src/main.c ... Archiving sys_mfg.a Archiving sys_sysinit.a Archiving util_mem.a Linking ~/dev/myproj/bin/targets/nrf52_boot/app/boot/mynewt/mynewt.elf Target successfully built: targets/nrf52_boot
2. Run the
newt build nrf52_bno055_test command to build the
$ newt build nrf52_bno055_test Building target targets/nrf52_bno055_test Compiling repos/mcuboot/boot/bootutil/src/image_ec.c Compiling repos/mcuboot/boot/bootutil/src/image_rsa.c Compiling repos/mcuboot/boot/bootutil/src/image_ec256.c Compiling repos/mcuboot/boot/bootutil/src/image_validate.c Compiling repos/mcuboot/boot/bootutil/src/bootutil_misc.c Compiling repos/apache-mynewt-core/apps/sensors_test/src/misc.c Compiling repos/apache-mynewt-core/apps/sensors_test/src/gatt_svr.c Compiling repos/apache-mynewt-core/apps/sensors_test/src/main.c ... Compiling repos/apache-mynewt-core/hw/drivers/sensors/bno055/src/bno055.c Compiling repos/apache-mynewt-core/hw/drivers/sensors/bno055/src/bno055_shell.c ... Compiling repos/apache-mynewt-core/hw/sensor/src/sensor.c Compiling repos/apache-mynewt-core/hw/sensor/src/sensor_oic.c Compiling repos/apache-mynewt-core/hw/sensor/src/sensor_shell.c Compiling repos/apache-mynewt-core/hw/sensor/creator/src/sensor_creator.c ... Archiving util_mem.a Archiving util_parse.a Linking ~/dev/myproj/bin/targets/nrf52_bno055_test/app/apps/sensors_test/sensors_test.elf Target successfully built: targets/nrf52_bno055_test
newt create-image command to create an image file. You may
assign an arbitrary version (e.g. 1.0.0) to the image.
$ newt create-image nrf52_bno055_test 1.0.0 App image succesfully generated: ~/dev/myproj/bin/targets/nrf52_bno055_test/app/apps/sensors_test/sensors_test.img
Connect the pins from the BNO055 sensor to the nRF52-DK board as specified in the following table:
Set up two connections between your computer and the nRF52-DK board:
A serial connection to communicate with the sensors_test application and view the sensor data and hardware information via the Mynewt shell.
You can reference the Serial Port Setup tutorial for more information on setting up a serial communication.
A connection from your computer to the micro-USB port on the nRF52-DK board to power the board and to load the bootloader and application image.
2. Turn the power on the board to ON. You should see the green LED light up on the board.
newt load nrf52_bootcommand to load the bootloader onto the board:
$ newt load nrf52_boot Loading bootloader $
2. Run the
newt load nrf52_bno055_test command to load the
application image on to the board:
$ newt load nrf52_bno055_test Loading app image into slot 1 $
Power the nRF52-DK board OFF and ON.
Start up a terminal emulator to connect the sensors_test application console. You can use one of the terminal emulators listed below or one of your choice:
On Mac OS and Linux platforms, you can run
minicom -D /dev/tty.usbserial-<port> -b 115200to connect to the console of your app. Note that on Linux, the format of the port name is
/dev/ttyUSB<N>, where N is a number.
On Windows, you can use a terminal application such as PuTTY to connect to the device.
If you located your port from a MinGW terminal, the port name format is
Nis a number. You must map the port name to a Windows COM port:
COM<N+1>. For example,
You can also use the Windows Device Manager to locate the COM port.
We use minicom for this tutorial. After minicom connects, enter
<return> to ensure the shell is running. You should see the
Welcome to minicom 2.7.1 OPTIONS: Compiled on May 17 2017, 15:29:14. Port /dev/tty.usbserial, 13:55:21 Press Meta-Z for help on special keys 010674 compat>
The sensor framework package implements the
sensor shell command. This command
allows you to:
List all the registered sensor devices.
View the sensor types that a registered sensor device supports.
Read sensor data samples.
To view the command syntax, enter
002340 Possible commands for sensor are: 002341 list 002341 list of sensors registered 002342 read <sensor_name> <type> [-n nsamples] [-i poll_itvl(ms)] [-d poll_du] 002344 read <no_of_samples> from sensor<sensor_name> of type:<type> at pr 002347 at <poll_interval> rate for <poll_duration> 002348 type <sensor_name> 002349 types supported by registered sensor 002350 compat>
You use the
sensor list command to list all the registered sensor devices:
031798 compat> sensor list 129441 sensor dev = bno055_0, configured type = 0x1 0x2 0x4 0x200 0x1000 0x2000 129444 compat>
The output shows one sensor, bno055_0, registered, and the configured types for the sensor. A configure type is a subset of the types that a sensor supports.
You use the
sensor type command to list the types that a sensor
031822 compat> sensor type bno055_0 033156 sensor dev = bno055_0, type = 033157 accelerometer: 0x1 033157 magnetic field: 0x2 033158 gyroscope: 0x4 033159 temperature: 0x10 033160 vector: 0x200 033160 accel: 0x1000 033161 gravity: 0x2000 033162 euler: 0x4000
You use the
sensor read command to
read data samples for a configured type. You can specify the number of
samples to read, a poll interval, and a poll duration. You can only view
sensor data for the sensor types that a sensor device is configured for.
Example 1: Read 5 samples of accelerometer data from the bno055_0 sensor:
033163 compat> sensor read bno055_0 0x1 -n 5 042974 ts: [ secs: 335 usecs: 745441 cputime: 336218225 ] 042976 x = -0.519999968 y = -7.289999968 z = 6.489999776 042978 ts: [ secs: 335 usecs: 771216 cputime: 336244000 ] 042979 x = -0.529999968 y = -7.360000128 z = 6.559999936 042981 ts: [ secs: 335 usecs: 794640 cputime: 336267424 ] 042982 x = -0.529999968 y = -7.340000160 z = 6.480000032 042983 ts: [ secs: 335 usecs: 810795 cputime: 336283579 ] 042984 x = -0.519999968 y = -7.300000192 z = 6.530000224 042986 ts: [ secs: 335 usecs: 833703 cputime: 336306487 ] 042987 x = -0.510000000 y = -7.309999936 z = 6.380000128
Each sample contains two lines of output. The first line is the time when the sample is read. The second line is the sample data. For the example output:
These two lines are for the first sample:
042974 ts: [ secs: 335 usecs: 745441 cputime: 336218225 ] 042976 x = -0.519999968 y = -7.289999968 z = 6.489999776
These two lines are for the last sample:
042986 ts: [ secs: 335 usecs: 833703 cputime: 336306487 ] 042987 x = -0.510000000 y = -7.309999936 z = 6.380000128
Example 2: Read the vector data at 20 ms poll interval. You can
q <return>, or
Q <return> to stop the polling.
002350 compat> sensor read bno055_0 0x200 -i 20 019271 ts: [ secs: 150 usecs: 560056 cputime: 151019584 ] 019272 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019274 ts: [ secs: 150 usecs: 580598 cputime: 151040126 ] 019275 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019277 ts: [ secs: 150 usecs: 604036 cputime: 151063564 ] 019278 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019280 ts: [ secs: 150 usecs: 627474 cputime: 151087002 ] 019281 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019283 ts: [ secs: 150 usecs: 650912 cputime: 151110440 ] 019284 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019286 ts: [ secs: 150 usecs: 674350 cputime: 151133878 ] 019287 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019289 ts: [ secs: 150 usecs: 697788 cputime: 151157316 ] 019290 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019292 ts: [ secs: 150 usecs: 721225 cputime: 151180753 ] 019293 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019295 ts: [ secs: 150 usecs: 744663 cputime: 151204191 ] 019296 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019298 ts: [ secs: 150 usecs: 768101 cputime: 151227629 ] 019299 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984 019301 ts: [ secs: 150 usecs: 791539 cputime: 151251067 ] 019302 x = 3.442626944 y = 0.026977540 z = 3.993286144 w = 0.829833984
The BNO055 device driver implements the
bno055 shell command
that allows you to:
Read sensor data samples for all the sensor types that the device supports.
sensorshell command discussed previously only reads sensor data for configured sensor types.
Query the chip id, sensor revisions, content of registers, sensor offsets.
Reset the device.
Change the power mode.
Change the operation mode.
bno055 to see the command syntax:
711258 bno055 cmd [flags...] 711259 cmd: 711259 r [n_samples] [ 0-acc | 1 -mag | 2 -gyro | 4 -tem| 9-quat | 26-linearacc | 27-gravity | 28-eul] 711264 mode [0-config | 1-acc | 2 -mag | 3 -gyro | 4 -acc| 5-accgyro | 6-maggyro | 7 -amg | 8 -imuplus | 9 -com| 9-m4g |11-NDOF_FMC_OFF | 12-NDOF ] 711269 chip_id 711270 rev 711270 reset 711270 pmode [0-normal | 1-lowpower | 2-suspend] 711272 sensor_offsets 711272 dumpreg [addr] \*\* Example 3: \*\* Query the device chip id:
711273 compat> bno055 chip_id 769056 0xA0
Example 4: View the sensor revisions:
827472 compat> bno055 rev 862354 accel_rev:0xFB mag_rev:0x32 gyro_rev:0x0F sw_rev:0x311 bl_rev:0x15
Now that you have successfully enabled an application to communicate with a sensor, We recommend that you:
Experiment with other
bno055shell commands in this tutorial to view other types of sensor data.
Change the default configuration values for the sensor. See the Changing the Default Configuration for a Sensor tutorial
Try a different off-board sensor. You can follow most of the procedures in this tutorial to enable other sensors in the sensors_test application. The
syscfg.ymlfile for the
hw/sensor/creator/package specifies the off-board sensors that Mynewt currently supports. You will need to:
<SENSORNAME>_OFBsetting to include the sensor driver package and to create and initialize the sensor device.
Enable the correct interface in the nRF52 BSP to communicate with the sensor device.
Enable the sensor device driver shell command if the driver supports the shell. You can check the
syscfg.ymlfile for the sensor device driver package in the
Try one of the other sensor tutorials listed in the Sensor Tutorials Overview