SLOU432B December   2015  – December 2021 DRV2625

 

  1. 1 Getting Started
    1. 1.1 Evaluation Module Operating Parameters
    2. 1.2 Quick Start Board Setup
  2. 2 DRV2625 Demonstration Program
    1. 2.1 Modes and Effects Table
    2. 2.2 Description of the Demo Modes
      1. 2.2.1 Mode Off – Haptics Effect Sequences
      2. 2.2.2 Mode 4 – ERM Clicks
      3. 2.2.3 Automatic Braking in Open Loop
      4. 2.2.4 Auto-Resonance Tracking
    3. 2.3 ROM Library Mode
    4. 2.4 Waveform Library Effects List
  3. 3 Additional Hardware Modes
    1. 3.1 Accessing GUI Mode
    2. 3.2 Accessing Bluetooth Mode
    3. 3.3 Haptics Control Console GUI
      1. 3.3.1 DRV2625 Console
  4. 4 Hardware Configuration
    1. 4.1 Input and Output Overview
    2. 4.2 Power Supply Selection
    3. 4.3 Using an External Actuator
    4. 4.4 PWM Input
    5. 4.5 External Trigger Control
      1. 4.5.1 MSP430 Trigger Control
      2. 4.5.2 External Source Trigger Control
    6. 4.6 External I2C Input
      1. 4.6.1 External I2C Control Initialization
    7. 4.7 Analog Input
  5. 5 Measurement and Analysis
    1. 5.1 Using Low-Pass Filter to Record Waveforms
  6. 6 Modifying or Reprogramming the Firmware
    1. 6.1 MSP430 Pin-Out
  7. 7 Schematic
  8. 8 Layout
  9. 9 Bill of Materials
  10. 10Revision History
  11. 11Trademarks

5.1 Using Low-Pass Filter to Record Waveforms

The DRV2625 drives LRA and ERM actuators using a 20-kHz PWM modulated waveform, but only the frequencies around the LRA resonant frequency or the ERM DC drive voltage are relevant to the haptic actuator vibration. The higher frequency switching content does not contribute to the vibration strength of the actuator and can make it difficult to interpret the modulated output waveform on an oscilloscope. The oscilloscope image on the left shows the DRV2625 unfiltered waveform and the image on the right shows a filtered version used for observation and measurement.

GUID-F7E7E80B-FCFB-4CE4-ADE2-E38C5FA39E46-low.pngFigure 5-2 DRV2625 Unfiltered Waveform
GUID-E6294897-C428-4355-9C7B-9066D0D5A6FB-low.pngFigure 5-3 DRV2625 Filtered Waveform

If the DRV2625EVM-CT filter is not used, TI recommends using a 1st-order, low-pass filter with a cutoff between 1kHz and 3.5kHz . Below is a recommended output filter for use while measuring and characterizing the DRV2625 in the lab.

GUID-4D4FD910-EB29-4DEE-A3CB-94DDEAF99738-low.gifFigure 5-4 Measuring the DRV2625 Output Signal with an Analog Low-Pass Filter