DRV2625 Datasheet, PDF (31/77 Pages) Texas Instruments – DRV2625 Ultra Low Power Closed-Loop LRA/ERM Haptic Driver with Built-In Library

www.ti.com
8.6.9 Waveform Setup and Playback
DRV2625
SLOS879A – DECEMBER 2015 – REVISED DECEMBER 2015
Playback of a haptic effect can occur in RTP mode or by using the waveform sequencer. And the process (either
RTP or waveform sequencer) can be triggered by writing a 1 to the GO bit, or by using the external trigger in
either trigger-pulse or trigger-level configuration. A waveform can be terminated prematurely by writing a 0 to the
GO bit or by sending a stop trigger via the external TRIG/INTZ pin.
8.6.9.1 Waveform Playback Using RTP Mode
The user can enter the RTP mode by writing to the MODE[1:0] parameter. In RTP mode, when the DRV2625
device received a trigger, the device drives the actuator continuously with the amplitude specified in the
RTP_INPUT[7:0] parameter. Because the amplitude tracks the value specified in the RTP_INPUT[7:0]
parameter, the I²C bus can stream waveforms. To stop driving the user can either change modes or send a stop
trigger (either write 0 to the GO bit or using the external trigger).
8.6.9.2 Waveform Sequencer
To play haptic effects from the internal memory, the effects must first be loaded into the waveform sequencer,
and then the effects can be launched by using any of the trigger options.
The waveform sequencer queues waveform-library identifiers for playback. Eight sequence registers queue up to
eight library waveforms for sequential playback. A waveform identifier is an integer value referring to the index
position of a waveform in the internal memory. Playback begins at WAV_FRM_SEQ1 when the user triggers the
waveform sequencer. When playback of that waveform ends, the waveform sequencer plays the next waveform
identifier held in WAV_FRM_SEQ2 (if non-zero). The waveform sequencer continues in this way until the
sequencer reaches an identifier value of zero or until all eight identifiers are played whichever comes first.
The waveform identifier is a 7-bit number. The MSB of each sequence register can be used to implement a delay
between sequence waveforms. When the MSB is high, bits 6-0 indicate the length of the wait time. The wait time
for that step then becomes WAV_FRM_SEQ[6:0] × 10 ms.
The DRV2625 device allows for looping of individual waveforms by using the WAVn_SEQ_LOOP parameters.
When used, the state machine will loop the particular waveform the number of times specified in the associated
WAVn_SEQ_LOOP parameter before moving to the next waveform. Additionally, the entire sequencer of
waveforms can be looped a number of times specified by the WAV_SEQ_MAIN_LOOP parameter. The
waveform-looping feature is useful for long, custom haptic playbacks, such as a haptic ringtone.
GO
Waveform Sequencer
RAM
WAV_FRM_SEQ0[7:0]
Effect 1
WAV_FRM_SEQ1[7:0]
Effect 2
WAV_FRM_SEQ2[7:0]
Effect 3
WAV_FRM_SEQ3[7:0]
Effect 4
WAV_FRM_SEQ4[7:0]
Effect 5
WAV_FRM_SEQ5[7:0]
WAV_FRM_SEQ6[7:0]
WAV_FRM_SEQ7[7:0]
Effect N
Figure 29. Waveform Sequencer Programming
8.6.9.3 Waveform Playback Triggers
The DRV2625 device has 2 modes of waveform playback: Waveform Sequencer and RTP. Both modes can be
triggered externally by using the TRIG/INTZ pin or internally by using the GO bit. If using external trigger, the
TRIG_PIN_FUNC most be selected appropriately.
Copyright © 2015, Texas Instruments Incorporated
Product Folder Links: DRV2625
Submit Documentation Feedback
31