7549 datasheet(52/86 Pages) RENESAS

52 / 86 page

Rev.2.02

Mar 31, 2009

Page 50 of 81

REJ03B0202-0202

7549 Group

Fig 65. Block diagram of internal clock generating circuit

“00”: Low-speed mode

High-speed on-chip

oscillator (HSOCO)

1/4

1/2

Timing

(Internal clock)

φSOURCE

“10”: High-speed mode

Clock division ratio selection bits

WIT

instruction

Low-speed on-chip

oscillator (LSOCO)

1/8

“01”: Middle-speed mode

“11”: Double-speed mode

Peripheral

function clock

generation circuit

(1/1 to 1/256)

Clock selection bits

High-speed on-chip oscillator

oscillation control bit

Low-speed on-chip oscillator

oscillation control bit

1/16

Prescaler 12

Timer 1

Oscillation stabilization time set timer

after release of the STP instruction

Reset

Interrupt disable flag I

Interrupt request

XIN/XCIN oscillation

control bit

Bits 0 and 1 of FSROM1: setting of the oscillation method select bits

“00”: Clock pins not used

P21/XIN/XCIN

Port P21

control circuit

P20/XOUT/XCOUT

Port P20

control circuit

“10”

“01”

“00”

It is not possible to write “1” to the low-speed on-chip

oscillator oscillation control bit if low-speed on-chip

oscillator stop has been disabled by bit 4 in FSROM2.

Also, the low-speed on-chip oscillator does not stop

even if the STP instruction is executed.

XIN oscillation cannot be

selected as

φSOURCE

if clock pins not used is

selected.

P21/XIN/XCIN

Port P21

control circuit

P20/XOUT/XCOUT

“11”: External clock input

Noise filter

P21/XIN/XCIN

P20/XOUT/XCOUT

“10”: 32 kHz quartz-

crystal oscillation

P21/XIN/XCIN

P20/XOUT/XCOUT

“01”: Ceramic or quartz-

crystal oscillation

1/1 to 1/256

Peripheral

function

(Note 2)

Reset

STP instruction

Notes 1: The oscillation circuit is built in the P20/XOUT/XCOUT pin and the P21/XIN/XCIN pin. When the Vcc of the microcomputer

is lower than the operation lower bound voltage even if these pins are used as I/O ports, the oscillation circuit is

connected and undefined values may be output from these pins.

2: Although a feed-back resistor exists on-chip, an external feed-back resistor may be needed depending on conditions.

7549 Datasheet(PDF) 52 Page - Renesas Technology Corp

7549 Datasheet(HTML) 52 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

Datasheet Download

Link URL