---
name: "struct_ff_periodic_effect"
section: "9"
platform: "linux"
package: "linux-manual-3.2"
version: "3.2.78-1"
release: "Debian 7 (Wheezy)"
platforms: ["linux"]
url: "https://new.carta.tech/struct_ff_periodic_effect"
---

# struct\_ff\_periodic\_effect(9)

defines parameters of a periodic force-feedback effect

## NAME

struct\_ff\_periodic\_effect - defines parameters of a periodic force-feedback effect

## SYNOPSIS

```
struct ff_periodic_effect {
  __u16 waveform;
  __u16 period;
  __s16 magnitude;
  __s16 offset;
  __u16 phase;
  struct ff_envelope envelope;
  __u32 custom_len;
  __s16 __user * custom_data;
};
```

## MEMBERS

waveform

kind of the effect (wave)

period

period of the wave (ms)

magnitude

peak value

offset

mean value of the wave (roughly)

phase

'horizontal' shift

envelope

envelope data

custom\_len

number of samples (FF\_CUSTOM only)

custom\_data

buffer of samples (FF\_CUSTOM only)

## DESCRIPTION

Known waveforms - FF\_SQUARE, FF\_TRIANGLE, FF\_SINE, FF\_SAW\_UP, FF\_SAW\_DOWN, FF\_CUSTOM. The exact syntax FF\_CUSTOM is undefined for the time being as no driver supports it yet.

## NOTE

the data pointed by custom\_data is copied by the driver. You can therefore dispose of the memory after the upload/update.

## COPYRIGHT