SH7721 datasheet(846/1524 Pages) RENESAS

Part #	SH7721

Description	Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series

PDF	1524 Pages

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Manufacturer	RENESAS [Renesas Technology Corp]

Direct Link	http://www.renesas.com

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846 / 1524 page

Section 24

USB Host Controller (USBH)

Rev. 3.00 Jan. 18, 2008 Page 784 of 1458

REJ09B0033-0300

24.3.16

Hc Fm Number b Register (USBHFN)

USBHFN 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

Bit

Bit Name

Initial

Value

R/W

Description

31 to 16



All 0

Reserved

These bits are always read as 0. The write value should

always be 0.

15 to 0

FN15 to FN0 All 0

R/W

Frame Number

These bits are incremented when USBHFN 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 FN 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 SF bit in USBHIS.

SH7721 Datasheet(PDF) 846 Page - Renesas Technology Corp