M32C87 datasheet(73/627 Pages) RENESAS

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M32C/87 Group (M32C/87, M32C/87A, M32C/87B)

6. Power Supply Voltage Detection Function

REJ09B0180-0151 Rev.1.51 Jul 31, 2008

Page 51 of 587

Power Supply Voltage Detection Function

The power supply voltage detection function has the Vdet3 detection function, Vdet4 detection function, and cold

start/warm start determination function. The Vdet3 detection function and Vdet4 detection function detect the changes

in voltage and trigger the events. The cold start/warm start determination function determines whether the MCU is

reset at power-on or reset while running.

The power supply voltage detection function is available only with VCC1 = 4.2V to 5.5V standard.

Figure 6.1 shows a block diagram of the voltage detection circuit. Figures 6.2 to 6.4 show registers associated with the

voltage detection function.

Figure 6.1

Power Supply Voltage Detection Function Block Diagram

CPU clock

1/2

Digital filter

Watchdog timer

interrupt signal

Vdet4 detection

interrupt signal

Oscillation stop

detection

interrupt signal

Watchdog timer

interrupt request

Vdet3 detection function

00b

01b

10b

11b

DF1 to DF0

1/2

1/8

(rejection range: 200 ns)

D40

D42 bit

CM10: bit in the CM1 register

VC13: bit in the VCR1 register

VC26, VC27: bits in the VCR2 register

DF1 and DF0, D40, D41, D42: bits in the D4INT register

WDC5: bit in the WDC register

NOTE:

1. When the VC27 bit in the VCR2 register is set to 0 (Vdet4 detection function not used), the Vdet4 detection signal becomes “H”.

WDC5

Write a given value to

the WDC register

COLD/WARM

(Cold start, warm start)

Hardware reset 1

at power-on

1 shot

Analog Filter

Internal reset signal

(active “L”)

Wait time to release hardware reset 2:

td(S-R)

VCC1

VC26

VC27

Vdet4 detection signal(1)

VC13

Cold start/warm start determination function

Vdet4 detection function

CM10

Latch

CM10

WAIT instruction (wait mode)

D41

≥

Vdet3

≥

Vdet3

Output one-shot pulse when the

D42 bit becomes 0 to 1.

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