DRV2604L Datasheet, PDF (16/73 Pages) Texas Instruments – DRV2604L 2- to 5.2-V Haptic Driver for LRA and ERM with Internal Memory and Smart-Loop Architecture

DRV2604L
SLOS866D – MAY 2014 – REVISED JUNE 2015
www.ti.com
Feature Description (continued)
8.3.5.2.2 Library Parameterization
The RAM waveforms are augmented by the time offset registers (registers 0x0D to 0x10). The augmentation
occurs only for the RAM waveforms and not for the other interfaces (such as PWM and RTP). The purpose of
the functionality is to add time stretching (or time shrinking) to the waveform. This functionality is useful for
customizing the entire library of waveforms for a specific actuator rise time and fall time.
The time parameters that can be stretched or shrunk include:
ODT
Overdrive time
SPT
Sustain positive time
SNT
Sustain Negative Time
BRT
Brake Time
The time values are additive offsets and are 8-bit signed values. The default offset of the time values is 0.
Positive values add and negative values subtract from the time value of the effect that is currently played. The
most positive value in the waveform is automatically interpreted as the overdrive time, and the most negative
value in the waveform is automatically interpreted as the brake time. The time-offset parameters are applied to
both voltage-time pairs and linear ramps. For linear ramps, linear interpolation is stretched (or shrunk) over the
two operative points for the period (see Equation 3).
t + t_(ofs)
where
• t_(ofs) is the time offset
(3)
Changing the playback interval can also manipulate the waveforms stored in memory. Each waveform in memory
has a granularity of 5 ms. If the user desires greater granularity, a 1-ms playback interval can be obtained by
asserting the PLAYBACK_INTERVAL bit in register 0x1F.
8.3.5.3 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 real-time playback register is sent directly to the playback engine. The amplitude
value is played until the user sends the device to standby mode or removes the device from RTP mode. The
RTP mode operates exactly like the PWM mode except that the user enters a register value over the I²C rather
than a duty cycle through the input pin. Therefore, 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 DRV2604L device automatically tracks the resonance frequency unless the LRA_OPEN_LOOP
bit is set (in register 0x1D). If the LRA_OPEN_LOOP bit is set, the LRA is driven according to the open-loop
frequency set in the OL_LRA_PERIOD[6:0] bit in register 0x20.
8.3.5.4 Analog Input Interface
When the DRV2604L device is in analog-input interface mode, the device accepts an analog voltage at the
IN/TRIG pin. The DRV2604L device drives the actuator continuously in analog-input interface mode until the user
sets the device to standby mode or to enter another interface mode. The reference voltage in standby mode is
1.8 V. Therefore, the 1.8-V reference voltage is interpreted as a 100% input value. A reference voltage of 0.9 V
is interpreted as a 50% input value and a reference voltage of 0 V is interpreted as a 0% input value. The input
value in standby mode is analogous to the duty-cycle percentage in PWM mode.
For the LRA, the DRV2604L automatically tracks the resonance frequency unless the LRA_OPEN_LOOP bit is
set (in register 0x1D). If the LRA_OPEN_LOOP bit is set, the LRA is driven according to the open-loop frequency
set in OL_LRA_PERIOD[6:0] bit in register 0x20.
16
Submit Documentation Feedback
Product Folder Links: DRV2604L
Copyright © 2014–2015, Texas Instruments Incorporated