Application writers can create their own effects by creating a custom force. A custom force is an array of constant force values played back by the device.
The type-specific structure for custom waveform effects is DICUSTOMFORCE.
Set the dwSamplePeriod member of the DICUSTOMFORCE structure and the dwSamplePeriod member of the DIEFFECT structure to the same value. This is the time, in milliseconds, for which each element in the array of forces is played.
The custom force is played repeatedly until the time set in the dwDuration member of the DIEFFECT structure has elapsed.