Acceleration (G)
Frequency (Hz)
DRV2605 Demonstration Program
The reason for higher acceleration can be seen in
. The LRA has a very-narrow operating
frequency range due to the properties of a spring-mass system. Furthermore, the resonance frequency
drifts over various conditions such as temperature and drive voltage (the effects shown in
). With
the smart loop auto-resonance feature, the DRV2605 dynamically tracks the exact resonant frequency to
maximize the vibration force.
Figure 11. LRA Acceleration versus Frequency over Output Voltage
and
show the difference between an ERM with automatic closed-loop overdrive and
braking, and the open-loop library waveform with a predefined overdrive period. The closed-loop version
starts and stops the actuator perfectly and does not drive too long or too short. Automatic overdrive and
braking simplify the design of haptic effects by eliminating the tuning time for actuator startup and stop.
Figure 12. ERM Closed Loop (Button 3)
Figure 13. ERM Open Loop (Button 4)
2.2.5
Mode 1 – Concentration Game
Mode 1 is a game that incorporates the various LRA and ERM effects. This can be used to demonstrate
haptics in a real application.
To begin playing Concentration:
1. Press any of the large effect buttons.
2. The game then counts down.
3. Once the countdown completes, a button lights and an effect plays.
4. Repeat the pattern by pressing the same buttons.
5. After each successfully repeated pattern, the board repeats the same pattern and adds one additional
button effect to the sequence.
10
DRV2605EVM-CT ERM and LRA Haptic Driver Evaluation Kit
SLOU348B – January 2013 – Revised March 2014
Copyright © 2013–2014, Texas Instruments Incorporated