WM8998 datasheet(82/307 Pages) WOLFSON

82 / 307 page

WM8998

Production Data

PD, October 2014, Rev 4.0

HAPTIC SIGNAL GENERATOR

The WM8998 incorporates a signal generator for use with haptic devices (eg. mechanical vibration

actuators). The haptic signal generator is compatible with both Eccentric Rotating Mass (ERM) and

Linear Resonant Actuator (LRA) haptic devices.

The haptic signal generator is highly configurable, and includes the capability to execute a

programmable event profile comprising three distinct operating phases.

The resonant frequency of the haptic signal output (for LRA devices) is selectable, providing support

for many different actuator components.

The haptic signal generator is a digital signal generator which is incorporated within the digital core of

the WM8998. The haptic signal may be routed, via one of the digital core output mixers, to a Class D

speaker output for connection to the external haptic device, as illustrated in Figure 31. (Note that the

digital PDM output paths may also be used for haptic signal output.)

Haptic Output (06h)

Haptic Signal

Generator

HAP_ACT

HAP_CTRL

ONESHOT_TRIG

LRA_FREQ

HAP_RATE

Digital Core Output Mixer

DAC

Output Volume

Class D Speaker Driver

DAC

OUTnxMIX_SRCn

OUTnxMIX_VOLn

Haptic Device

Figure 31 Digital Core Haptic Signal Generator

The bracketed number (06h) in Figure 31 indicates the corresponding *_SRCn register setting for

selection of the haptic signal generator as an input to another digital core function.

The haptic signal generator is selected as input to one of the digital core output mixers by setting the

*_SRCn register of the applicable output mixer to (06h).

The sample rate for the haptic signal generator is configured using the HAP_RATE register - see

Table 19. Note that sample rate conversion is required when routing the haptic signal generator

output to any signal chain that is asynchronous and/or configured for a different sample rate.

The haptic signal generator is configured for an ERM or LRA actuator using the HAP_ACT register bit.

The required resonant frequency is configured using the LRA_FREQ field. (Note that the resonant

frequency is only applicable to LRA actuators.)

The signal generator can be enabled in Continuous mode or configured for One-Shot mode using the

HAP_CTRL register, as described in Table 17. In One-Shot mode, the output is triggered by writing to

the ONESHOT_TRIG bit.

In One-Shot mode, the signal generator profile comprises the distinct phases (1, 2, 3). The duration

and intensity of each output phase is programmable.

In Continuous mode, the signal intensity is controlled using the PHASE2_INTENSITY field only.

In the case of an ERM actuator (HAP_ACT = 0), the haptic output is a DC signal level, which may be

positive or negative, as selected by the *_INTENSITY registers.

For an LRA actuator (HAP_ACT = 1), the haptic output is an AC signal; selecting a negative signal

level corresponds to a 180 degree phase inversion. In some applications, phase inversion may be

desirable during the final phase, to halt the physical motion of the haptic device.

WM8998 Datasheet(PDF) 82 Page - Wolfson Microelectronics plc

WM8998 Datasheet(HTML) 82 Page - Wolfson Microelectronics plc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL