7643 datasheet(63/424 Pages) RENESAS

63 / 424 page

Rev.2.00

Aug 28, 2006

page 46 of 103

REJ09B0133-0200

OVERVIEW

FUNCTIONAL DESCRIPTION

7643 Group

Set the USB resume signal interrupt status flag to “0” after the

wake-up sequence process. The USB resume detect flag goes to

“0” at the same time. When the clock operation is started up with

a remote wake-up, set the USB remote wake-up bit to “1” after the

wake-up sequence process. (keep it set to “1” for a minimum of 10

ms and maximum of 15 ms). By doing this, the MCU will send a

resume signal to the host CPU and let it know that the suspend

state has been released.

After that, set the USB remote wake-up bit and the USB suspend

detection flag to “0”, because the USB suspend detection flag is

not automatically cleared to “0” with a remote wake-up.

[USB Control Register] USBC

When using the USB function, the USB enable bit must be set to

“1”. The USB line driver supply bit must be set to “0” (DC-DC con-

verter is disabled) when operating at Vcc = 3.3V. In this condition,

the setting of the USB line driver current control bit has no effect

on USB operations.

Fig. 35 Structure of USB control register

USB control register (address 001316)

USBC

Reserved bit (“0” at read/write)

USB default state selection bit (USBC1)

0: In default state after power-on/reset

1: In default state after USB reset signal received (Note 1)

Reserved bit (“0” at read/write)

USB line driver current control bit (USBC3)

0: High current mode

1: Low current mode

USB line driver supply enable bit (USBC4) (Note 2)

0: Line driver disabled

1: Line driver enabled

USB clock enable bit (USBC5)

0: 48 MHz clock to the USB block disabled

1: 48 MHz clock to the USB block enabled

Reserved bit (“0” at read/write)

USB enable bit (USBC7)

0: USB block disabled (Note 3)

1: USB block enabled

Notes 1: Without regard to this bit, USB internal registers (address 005016 to 005F16) go into the states at

reset (default) at the same time when USB reset is detected.

2: When using the MCU in Vcc = 3.3 V, set this bit to “0” and disable the built-in DC-DC converter

3: Setting this bit to 0” causes the contents of all USB registers to have the values at reset.

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