DRV2605L Datasheet, PDF (15/69 Pages) Texas Instruments – DRV2605L 2 to 5.2 V Haptic Driver for LRA and ERM With Effect Library and Smart-Loop Architecture

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DRV2605L
SLOS854C – MAY 2014 – REVISED SEPTEMBER 2014
Feature Description (continued)
LIBRARY
E
F
Table 1. ERM Library Table (continued)
RATED VOLTAGE
3V
4.5 V
OVERDRIVE VOLTAGE
3V
5V
RISE TIME
> 140 ms
35 ms to 45 ms
BRAKE TIME
> 30 ms
10 ms to 20 ms
8.3.5.2.1 Waveform Sequencer
The waveform sequencer queues waveform identifiers for playback. Eight sequence registers queue up to eight
waveforms for sequential playback. A waveform identifier is an integer value referring to the index position of a
waveform in the ROM library. Playback begins at register address 0x04 when the user asserts the GO bit
(register 0x0C). When playback of that waveform ends, the waveform sequencer plays the waveform identifier
held in register 0x05 if the next waveform is non-zero. The waveform sequencer continues in this way until it
reaches an identifier value of zero or until all eight identifiers are played (register addresses 0x04 through 0x0B),
whichever scenario is reached first.
The waveform identifier range is 1 to 127. The MSB of each sequence register can 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.
8.3.5.2.2 Library Parameterization
The ROM waveforms are augmented by the time offset registers (registers 0x0D to 0x10). This augmentation
occurs only for the ROM waveforms and not for the other interfaces (such as PWM and RTP). The purpose of
this 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 these 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. These 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 which is one of the previously listed time parameters
(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. This 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.
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