USB_FrameSyncNumber (SWI&55391)
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USB_FrameSyncNumber (SWI&55391)

USB_FrameSyncNumber (SWI&55391) — Tells the USB Module the current USB frame number for a given USB host controller driver.

On Entry

R0Pointer to controller structure.
R1actual USB frame number
R2Reserved. Must be set to zero.
R3Reserved. Must be set to zero.

On Exit

R0preserved
R1Error code Table A.1, “Error codes used by the USB system”
R2, R3Preserved

Use

An USB host controller driver must tell the actual USB frame number every time if a new frame is starting at its USB. This causes a lot of action internal in the USB module. Note that the number given must not exceed the limit given by the frame number mask of the USB host controller properties.

Related SWI's

None.

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