M32CSLASH8B datasheet(54/406 Pages) RENESAS

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M32C/8B Group

6. Power Supply Voltage Monitor Function

Preliminary specification

Specifications in this manual are tentative and subject to change.

REJ09B0450-0050 Rev.0.50 Oct 31, 2008

Page 37 of 385

Power Supply Voltage Monitor Function

Edge

generation

circuit

Watchdog timer interrupt

signal

Voltage monitor

interrupt signal

Oscillation stop

detection

interrupt signal

LVDIEN bit

VDEN bit, LVDIEN bit, LVDF flag, and VMF flag: Bits in the LVDC register

RVC3 to RVC0: Bits in the DVCR register

NOTE:

1. When the VDEN bit in the LVDC register is set to 0, (Voltage monitor function not used), Vdet detection signal becomes “H”

and the VMF bit becomes 1.

VCC1

Vdet detection

signal(1)

Voltage Monitor Function

≥ Vdet

VDEN bit

RVC3 to RVC0

VMF flag

LVDF flag

Watchdog timer

interrupt request

The power supply voltage monitor function detects the changes in voltage and triggers the interrupts.

Figure 6.1 shows a block diagram of the voltage monitor function. Figures 6.2 and 6.3 show registers associated with

the function.

Figure 6.1

Power Supply Voltage Monitor Function Block Diagram

b6 b5 b4

Symbol

LVDC

Bit Symbol

Bit Name

VDEN

Function

Voltage monitor function select

bit(2)

LVDIEN

0: Voltage monitor interrupt disabled

1: Voltage monitor interrupt enabled

Voltage monitor interrupt

enable bit

−

(b7-b4)

Reserved bits

Set to 0

0 0

Voltage Monitor Register(1)

NOTES:

1. Set the LVDC register after setting the PRC3 bit in the PRCR register is set to 1 (write enable).

2. Wait for td(E-A) to elapse after the VDEN bit is set to 1 to use the voltage monitor function. To set the LVDIEN bit to 1, wait for

td(E-A) to elapse after the VDEN bit is set to 1.

3. Bits LVDF and VMF are enabled when the VDEN bit is 1. When the VDEN bit is 0, the LVDF bit becomes 0 and the VMF bit

becomes 1.

4. The LVDF bit can be set to 0 by a program. Writing a 1 has no effect.

0: Voltage monitor function not used

1: Voltage monitor function used

VMF

0: VCC1

< Vdet (F)

1: VCC1

≥ Vdet (R)

Voltage change monitor flag(3)

LVDF

0: Not detected

1: Voltage crosses Vdet

Voltage change detect flag(3)(4)

Address

001Bh

After Reset

0000 1000b

Figure 6.2

LVDC Register

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