HD6417727BP160CV Datasheet, PDF (803/1098 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family/ SH7700 Series

Section 24 USB HOST Module
24.2.16 HcFmNumber
HcFmNumberb Register (H'040004BC)
The HcFmNumber register is a 16-bit counter. It indicates the reference of timing between events
occurring in the host controller and host controller driver. The host controller driver uses a 16-bit
value specified in this register and generates a 32-bit frame number without necessity for a
frequent access to the register.
Register: HcFmNumber
Bits
Reset R/W
31–16 0h
—
15–0
0b
R
Offset: 3C–3F
Description
Reserved.
FrameNumber (FN)
These bits are incremented when HcFmRemaining is reloaded.
The count will return to H'0 after H'FFFF. When the host
controller transits to the UsbOperational state, these bits are
automatically incremented. After the host controller increments
the FramNumber bit and sends SOF in each frame boundary,
the content is written to HCCA before the host controller reads
first ED in the frame. After writing to HCCA, the host controller
sets the StartofFrame bit in the HcInterruptStatus register.
Rev.6.00 Mar. 27, 2009 Page 745 of 1036
REJ09B0254-0600