DRV2624 Datasheet, PDF (15/79 Pages) Texas Instruments – DRV2624 Ultra Low Power Closed-Loop LRA/ERM Haptic Driver with Internal Memory

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DRV2624
SLOS893A – DECEMBER 2015 – REVISED DECEMBER 2015
Feature Description (continued)
The DRV2624 also allows for looping the entire waveform sequencer by configuring the WAV_SEQ_MAIN
parameter. In this case, the waveform sequencer will loop all valid WAV_FRM_SEQn identifiers according to the
number specified in the WAV_SEQ_MAIN. For example, if the first and second identifiers are valid (for example
1 and 2), the third identifier is 0 (signaling to stop), and the WAV_SEQ_MAIN is configured to loop once (play the
waveform sequence twice), then the DRV2624 device will play waveform 1, then waveform 2, then waveform 1
then waveform 2, and then go to standby.
8.3.4.2 Real-Time Playback (RTP) Interface
The real-time playback mode is a simple, single 8-bit register interface that holds an amplitude value. When real-
time playback is enabled, the RTP_INPUT parameter, which represents an amplitude value, is sent directly to the
playback engine. Once triggered, the value is played until the user sends a stop trigger or removes the device
from RTP mode. The RTP mode is a digital streaming mode where the user enters a register value over the I²C.
Because of the similarity between RTP mode and legacy PWM modes, any API (application-programming
interface) designed for use with a PWM generator in the host processor can write the data values over the I²C
rather than writing the data values to the host timer. This ability frees a timer in the host while retaining
compatibility with the original software.
For the LRA, the DRV2624 device automatically tracks the resonance frequency unless the CONTROL_LOOP
bit is set to open loop operation. If the CONTROL_LOOP bit is set to open loop, the LRA is driven according to
the open-loop frequency set in the OL_LRA_PERIOD parameter.
8.3.4.3 Process Trigger
All processes (RTP, Waveform Sequencer, Calibration and Diagnostics) in the DRV2624 device are triggered
processes, which means that the user has to trigger the process before the process begins. A trigger can be
achieved by software using the GO bit, or by hardware using the TRIG/INTZ pin. The process stops once it
finishes, or if a stop trigger is sent. For information on external trigger functionality refer to Multi-Purpose Pin
Functionality.
A typical process (either RTP, Waveform Sequencer, Calibration or Diagnostics) will start and end follwing the
diagram in Figure 18.
Get into Mode
Wait for Trigger in Standby Mode
/ Process Done
/ Trigger Received
/ Trigger Cancellation Received
Play Process
Figure 18. Typical Process Execution
8.3.5 Noise Gate Control
The DRV2624 device features a noise gate that filters out any voltage smaller than a particular threshold to
prevent unintended vibrations. The NG_THRESH bit controls the threshold.
8.3.6 Edge Rate Control
The DRV2624 output driver implements edge rate control (ERC). This control ensures that the rise and fall
characteristics of the output drivers do not emit levels of radiation that could interfere with other circuitry common
in mobile and portable platforms. Because of ERC most system do not require external output filters, capacitors,
or ferrite beads.
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