7733 datasheet(374/940 Pages) RENESAS

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CLOCK GENERATING CIRCUIT

7733 Group User’s Manual

14–11

14.3.2 System clock switching procedure

Figures 14.3.6 to 14.3.8 show the system clock switching procedure.

14.3 Clock control

Fig. 14.3.6 System clock switching procedure (1)

State of bits 4 to 1 of the oscillation circuit control register 0 when switching the system clock

Stopped

Operating

Port-Xc selection bit (bit 4)

System clock selection bit (bit 3)

Main clock stop bit (bit 2)

(Sub-clock oscillation circuit: Oscillating)

(Main clock)

(Sub clock)

(Main clock)

(Stopped)

(Oscillating)

“1”

“0”

“1”

“0”

“1”

“0”

System clock

Main clock

Sub clock

Main clock

(Main-clock oscillation

circuit: Oscillating)

Oscillation of the main-clock oscillation circuit

Oscillation stabilizing time

Stopped

Operating

Oscillation of the sub-clock oscillation circuit

Oscillation stabilizing time

Notes 1: Before selecting the sub clock, make sure that oscillation of the sub clock is fully stabilized after oscillation starts.

2: Before selecting the main clock, make sure that oscillation of the main clock is fully stabilized after oscillation restarts.

(Note 1)

(Note 2)

7733 Datasheet(PDF) 374 Page - Renesas Technology Corp