Renesas M16C FAMILY Manual de usuario descargar pdf (Pagina 13)

■ REASON #7: RELIABLE

Normal XIN

oscillation

Abnormal XIN

oscillation

XIN

On-chip

oscillator

CPU

XIN

Back-up by the

internal on-chip

oscillator

XIN

On-chip

oscillator

CPU

On-chip

oscillator

Settable Count Value

CPU Clock

Dedicated

On-chip

Oscillator

MUX

WATCHDOG TIMER

Reload

CLK

Underflow

Reset or

Interrupt

Signal

VCC [V]

Internal

status

(2 options)

(16 options)

(4 options)

reset

Vdet2

Vdet1

Vdet0

reset

Program execution

Interrupt

No Vcc rise time condition

required for Power-on reset

Reset Detection

Settings available from 2.20V to 4.45V

(with 0.15V interval)

Low-voltage Detection

(1/fosc-s) x 8

When out of control

Important register

CPU

Normal Procedure

CPU

Important register

Protect

1) Unlock

2) Register setting

Top Reasons to Select the M16C Platform

™

Oscillation Stop Detection

Upon the detection of abnormal

operation of the external oscillator, the

M16C devices can automatically

switch to the high-speed, highly

accurate on-chip oscillator. Thus,

system operation can be maintained

and a graceful shut-down can be

accomplished, if necessary.

Enhanced Watchdog Timer (WDT)

WDTs in M16C devices provide enhanced function-

ality such as automatic run after reset is released.

They can also be initiated by software. In addition,

for added reliability, a dedicated low-speed on-chip

oscillator (125kHz) can be selected as the clock

source, ensuring operation independent from

external clocks.

Power Supply Monitoring

(R8C/3x only)

The Power Supply Monitoring circuitry in M16C

devices can be used for Power-On Reset (POR) and

Low-Voltage Detect (LVD) functions. Three different

detection levels can be enabled to detect rising or falling

voltage. If the system’s power supply fluctuates beyond

normal levels, the circuit can generate an interrupt

signal to notify of a malfunction or can RESET the

MCU to prevent an undesirable operating condition.

System Operation Access Control

The contents of Special Function Registers (SFRs)

can be protected from undesirable access. System

critical registers that configure operations such as

system clock control, power supply monitoring and

others can be set to read-only by using the Access

Control Register (PRCR).

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 ... 45 46

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Renesas M16C FAMILY Manual de usuario Pagina 13

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