M66291GP datasheet(13/126 Pages) RENESAS

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M66291GP/HP

Rev 1.01 2004.11.01 page 13 of 122

(3) Xtal (Clock Select) Bits (b13~b12)

These bits set the multiplication factor of the external clock into PLL.

Since it is necessary to supply 48 MHz to the core block, the setting values of these bits are determined by the

clock frequency to be input into the PLL.

Refer to Figure 2.3.

(4) SCKE (Internal Clock Enable) Bit (b11)

This bit sets the clock supply into the core block.

Set the PLLC bit to “1” and wait until the oscillation of the PLL stabilizes before setting this bit to “1”.

Refer to Figure 2.3.

O scillation

buffer

XCKE bit

PLL

External clock

PLLC bit

Enable/Disable

SCKE bit

Xtal bits

Multiplying

factor

Core block

I/O block

Enable/Disable

Figure 2.3 Clock Control

(5) USBPC (USB Transceiver Power Control) Bit (b10)

This bit sets the enable/disable of the USB transceiver block of I/O block.

Even if this bit is set to “0”, it is possible to receive the resume signal during the Suspended state (DVSQ bits

= “1xx”). It is necessary that the Tr_on bits be set to “x1” (during operation of SIE block).

(6) Tr_on (Tr_on Output Control) Bits (b9~b8)

These bits set the TrON signal output from I/O block and the enable/disable of SIE block in core block.

(7) USBE (USB Module Operation Enable) Bit (b0)

This bit sets S/W reset.

When this bit is set to “0”, the M66291 enters the S/W reset state and the registers are set to their S/W reset

state.

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