7643 datasheet(225/424 Pages) RENESAS

225 / 424 page

Rev.2.00

Aug 28, 2006

page 104 of 202

7643 Group

REJ09B0133-0200

APPLICATION

2.6 USB

Fig. 2.6.7 Structure of USB control register

USB control register

b7 b6 b5 b4 b3 b2 b1 b0

USB control register

(USBC : address 1316)

Name

Functions

At reset R W

USB line driver current

control bit (USBC3)

USB line driver supply

enable bit (USBC4) (Note 2)

0 : In default state after power-on/reset

1 : In default state after USB reset signal

received (Note 1)

0 : High current mode

1 : Low current mode

0 : Line driver disabled

1 : Line driver enabled

0 : 48 MHz clock to the USB block disabled

1 : 48 MHz clock to the USB block enabled

USB enable bit (USBC7)

0 : USB block disabled (Note 3)

1 : USB block enabled

USB default state selection

bit (USBC1)

USB clock enable bit

(USBC5)

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.

Nothing is arranged for this bit.

Fix this bit to “0”.

Nothing is arranged for this bit.

Fix this bit to “0”.

Nothing is arranged for this bit.

Fix this bit to “0”.

2.6.3 Related registers

(1)

USB control register

This register is used for all operation controls performed by the USB function control unit (USB

FCU). USB reset does not affect this register.

q USB default state selection bit

This bit selects the cases in which the USB core state machine ‘state’ (the section that controls

transitions of the USB core state) will return to the default state. However, without regard to this

bit, USB internal registers (addresses 005016 to 005F16) go into the states at reset (default state)

at the same time when USB reset is detected.

When this bit is “0”, the state returns to the default state at power-on/reset.

When this bit is “1”, the state returns to the default state when the USB reset is received

(recommended).

q USB line driver current control bit

This bit is used to reduce the amount of USB dissipation power.

Set to “1” for the suspend state, but always set to “0” for USB control operations.

When using the MCU in Vcc = 3.3V, the value of this bit does not affect USB operations.

q USB line driver supply enable bit

Set this bit to “1” to use the USB built-in DC-DC converter when using the MCU in Vcc = 5V.

The built-in DC-DC converter is disabled when this bit is “0”; therefore, set to “0” when using

the MCU in Vcc = 3.3V.

q USB clock enable bit

Set this bit to “1” to enable the USB clock.

q USB enable bit

Set to “1” to enable the USB function. Make sure you include a 250ns wait after setting the bit

to “1” to read from/write to other USB-related registers.

Figure 2.6.7 shows the structure of USB control related register.

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