Enabling and Calibrating Off-Board DRV2605 LRA Actuator

This tutorial shows you how to run the sensors_test application on an nRF52-DK board to communicate, via the I2C interface, with the Adafruit DRV2605 device. The DRV2605 driver includes the drv2605 shell command that allows you to quickly to view the status, calibrate and actuate your motor in preperation for using it programmatically in your own app.

This tutorial shows you how to:

  • Create and build the application and bootloader targets.

  • Connect a DRV2605 actuator device to an nRF52-DK board.

  • Run drv2605 shell commands to view the actuator data and control the drv2605 device.

Prerequisites

Step 1: Creating the Application Target

In this step, you create a target for the sensors_test application that enables the DRV2605 off-board device.

To add the DRV2605 device 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.

  • DRV2605_OFB: Enables support for the DRV2605 actuator in the sensor creator package (hw/sensor/creator).
    When this setting is enabled, the creator package performs the following:

    • Includes the DRV2605 driver package (hw/drivers/drv2605) as a package dependency.

    • Creates an os device for the device in the Mynewt kernel.

    • Configures the device with default values.

  • DRV2605_CLI: Enables the drv2605 shell command in the DRV2605 device driver package. The sensors_test application also uses this setting to conditionally include the call to the drv2605_shell_init() function to initialize the shell support in the driver.

  • DRV2605_EN_PIN: The pin the driver needs to gpio in order to enable your DRV2605 device.

  • DRV2605_RATED_VOLTAGE: I have no easy default for you here, it is entirelay based on your purchased LRA motor. See 8.5.2.1 Rated Voltage Programming in the TI DRV2605 Datasheet or maybe talk to your motor supplier.

  • DRV2605_OD_CLAMP: I have no easy default for you here, it is entirelay based on your purchased LRA motor. See 8.5.2.2 Overdrive Voltage-Clamp Programming in the TI DRV2605 Datasheet or maybe talk to your motor supplier. NOTE: LRA and ERM (8) and (9) equations are swapped in the datasheet revision “SLOS854C REVISED SEPTEMBER 2014”

  • DRV2605_DRIVE_TIME: I have no easy default for you here, it is entirelay based on your purchased LRA motor. See 8.6.21, but generally it is computable with the equation LRA DRIVE_TIME = (0.5 × (1/fLRA * 1000) - 0.5 ms) / 0.1 ms

1. Run the newt target create command, from your project base directory, to create the target. We name the target nrf52_drv2605_test:

$ newt target create nrf52_drv2605_test
Target targets/nrf52_drv2605_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_drv2605_test app=@apache-mynewt-core/apps/sensors_test bsp=@apache-mynewt-core/hw/bsp/nrf52dk build_profile=debug
Target targets/nrf52_drv2605_test successfully set target.app to @apache-mynewt-core/apps/sensors_test
Target targets/nrf52_drv2605_test successfully set target.bsp to @apache-mynewt-core/hw/bsp/nrf52dk
Target targets/nrf52_drv2605_test successfully set target.build_profile to debug

$

3. Run the newt target set command to enable the I2C_0, DRV2605_OFB, DRV2605_CLI, DRV2605_EN_PIN, DRV2605_RATED_VOLTAGE, DRV2605_OD_CLAMP, and DRV2605_DRIVE_TIME syscfg settings:

$ newt target set nrf52_drv2605_test syscfg=DRV2605_OFB=1:I2C_0=1:DRV2605_CLI=1:DRV2605_EN_PIN=3:DRV2605_RATED_VOLTAGE=0x53:DRV2605_OD_CLAMP=0x69:DRV2605_DRIVE_TIME=20
Target targets/nrf52_drv2605_test successfully set target.syscfg to DRV2605_OFB=1:I2C_0=1:DRV2605_CLI=1:DRV2605_EN_PIN=3:DRV2605_RATED_VOLTAGE=0x53:DRV2605_OD_CLAMP=0x69:DRV2605_DRIVE_TIME=20

$

Step 2: Creating an Application Image and loading it

This tutorial assumes you have a functioning bootloader as taught in add an offboard sensor Now run the newt create-image command to create an image file. You may assign an arbitrary version (e.g. 1.0.0) to the image.

$ newt build nrf52_drv2605_test && newt create-image nrf52_drv2605_test 1.0.0
App image succesfully generated: ~/dev/myproj/bin/targets/nrf52_drv2605_test/app/apps/sensors_test/sensors_test.img

Step 3: Communicating with and Calibrating the DRV2605 device

This tutorial assumes you have a functioning application console as taught in add an offboard sensor The DRV2605 device driver implements the drv2605 shell command that allows you to:

  • Query the chip id, content of registers, calibrations.

  • Reset the device.

  • Change the power mode.

  • Change the operation mode.

  • Load waveforms to actuate.

  • Actuate the device.

Example 1: Query the device chip id:

711273 compat> drv2605 chip_id
769056 0x07

Example 2: Run Diagnostics on your motor setup numbers:

827472 compat> drv2605 op_mode diag
drv2605 op_mode diag
829717 op_mode succeeded

If that didn’t work or you will have to compute different DRV2605_RATED_VOLTAGE, DRV2605_OD_CLAMP, and DRV2605_DRIVE_TIME values and try again or maybe talk to your motor manufacturer or TI for more help.

Example 3: Run Calibration on your motor: Theres a lot more setup numbers you could enter here for the DRV2605 to figure out how to actuate your motor, but some of them it can figure out itself through auto calibration. Lets run autocalibration and then dump the fresh calibration numbers:

001407 compat> drv2605 op_mode cal
drv2605 op_mode cal
001931 op_mode succeeded
drv2605 dump_cal
DRV2605_CALIBRATED_COMP: 0x09
DRV2605_CALIBRATED_BEMF: 0x79
DRV2605_CALIBRATED_BEMF_GAIN: 1

You could programmatically run this on every startup, but more likely you’d want to save these as in your syscfg.yml and restart. Presumably you’d never have to do these steps ever again.

Step 4: Actually Actuate

Now you’re ready to (sigh) rumble. One way to use the DRV2605 device is to enable the ROM mode to use its stored patterns. Technically you dont need to do this after first configure as ROM mode is the default mode:

021773 compat> drv2605 op_mode rom
drv2605 op_mode rom
037245 op_mode succeeded

Now you can load up to 8 internal roms or delays. In this case we’ll use four hard clicks (1) with max delays (255) in between. You may only have to do this once per boot if you wanted to use this same sequence every time you trigger the DRV2605 device.

120858 compat> drv2605 load_rom 1 255 1 255 1 255 1 255
drv2605 load_rom 1 255 1 255 1 255 1 255
122555 Load succeeded

The motor is in standby by default after a mode change, so enable it:

002111 compat> drv2605 power_mode active
drv2605 power_mode active
003263 power_mode succeeded

Now you can trigger those forms as many times as you want or load new forms and trigger again:

122555 compat> drv2605 trigger
drv2605 trigger
128806 Trigger succeeded

Conclusion

You’ve successfully enabled a mynewt application to communicate with a drv2605 device, calibrated it and actuated a motor! Next youll want to look at the code comments on the drv2605.c file and how the drv2605_shell.c file is implemented so you can setup and actuate your device programmatically within your application.