7477 datasheet(170/354 Pages) RENESAS

170 / 354 page

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7470/7471/7477/7478 GROUP USER’S MANUAL

HARDWARE

1.16 Oscillation circuit

The 7470/7471/7477/7478 group has the following circuits to obtain clocks required for operations.

• 7470/7477 group: Main clock oscillation circuit

• 7471/7478 group: Main clock oscillation circuit and sub-clock oscillation circuit

1.16.1 Oscillation circuit

(1) Clock generating circuit

The clock generating circuit controls the oscillation of the oscillation circuit and a generated clock

(internal clock

φ) is supplied to the CPU and peripheral units.

Figure 1.16.1 shows a clock generating circuit block diagram.

Fig. 1.16.1 Clock generating circuit block diagram

1/2

XIN

XOUT

XCIN

XCOUT

Timer 3 count stop bit

(T34M0)

T34M1

T34M2

Internal clock

Internal system clock

selection bit (CM7)

Internal system clock selection bit (CM 7)

Main clock (XIN–XOUT) stop bit (CM6)

STP instruction

WIT instruction

1/2

1/8

Timer 3

Timer 4

CNTR1

Timer 1 or timer 2

overflow signal

Timer 4 count stop bit

(T34M3)

Reset

Interrupt disable flag I

Reset

Interrupt request

Timer 4 count source selection bits

T34M4

T34M5

Timer 3 count

source

selection bits

STP

instruction

Note : The 7470/7477 group is not provided with pins XCIN and XCOUT.

7477 Datasheet(PDF) 170 Page - Renesas Technology Corp

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