DRV2624 Datasheet, PDF (31/79 Pages) Texas Instruments – DRV2624 Ultra Low Power Closed-Loop LRA/ERM Haptic Driver with Internal Memory

www.ti.com
8.6.9 Waveform Setup and Playback
DRV2624
SLOS893A – 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 DRV2624
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 Loading Data to RAM
The DRV2624 device contains 1 kB of integrated RAM to store customer waveforms. The waveforms are
represented as amplitude-time pairs. Using the waveform sequencer, the waveforms can be recalled,
sequenced, and played through the I²C or an external GPIO trigger.
A library consists of a revision byte (should be set to 0), a header section, and the waveform data content. The
library header defines the data boundaries for each effect ID in the data field, and the waveform data contains a
sequence of amplitude-time pairs that define the effects.
RAM
0x000
Revision
Header
Waveform Data
0x7FF
Figure 29. RAM Memory Structure
8.6.9.2.1 Header Format
The header block consist of N-boundary definition blocks of 3 bytes each. N is the number of effects stored in the
RAM (N cannot exceed 127). Each of the boundary definition blocks contain the start address (2 bytes) and a
configuration byte.
The start address contains the location in the memory where the waveform data associated with this effect
begins. The position of the effect pointer in the header becomes the effect ID. The first effect boundary definition
points to the ID for effect 1, the second definition points to the ID for effect 2, and so on. The resulting effect ID is
the effect ID that is used in the waveform sequencer.
Copyright © 2015, Texas Instruments Incorporated
Product Folder Links: DRV2624
Submit Documentation Feedback
31