M32CSLASH86T datasheet(71/505 Pages) RENESAS

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Page 48

6. Voltage Detection Circuit

)

(

6.1.1 Limitations on Exiting Stop/Wait Mode

The low voltage detection interrupt is generated and the microcomputer exits stop mode as soon as the

CM10 bit in the CM1 register is set to "1" (all clocks stopped) under the conditions below. Additionally, if

WAIT instruction is executed under these same conditions, the low voltage detection interrupt is immedi-

ately generated and the microcomputer exits wait mode.

- the VC27 bit in the VCR2 register is set to "1" (low voltage detection circuit enabled),

- the D40 bit in the D4INT register is set to "1" (low voltage detection interrupt enabled),

- the D41 bit in the D4INT register is set to "1" (low voltage detection interrupt is used to exit stop/wait

mode), and

- the voltage applied to the VCC pin is higher than Vdet4 (the VC13 bit in the VCR1 register is set to "1")

Set the CM10 bit to "1" when the VC13 bit is "0" (VCC < Vdet4), if the microcomputer is set to enter stop/

wait mode when the voltage applied to the VCC pin drops below Vdet4 and to exit stop/wait mode when

the voltage applied rises to Vdet4 or above.

6.2 Cold Start-up / Warm Start-up Determine Function

The WDC5 bit in the WDC register determines either cold start-up, power-on reset, or warm start-up, reset

during the microcomputer running. Default value of the WDC5 bit is "0" (cold start-up) when power-on. It is

set to "1" (warm start-up) by writing desired values to the WDC register. The WDC5 bit is not reset,

regardless of a software reset or reset signal input.

Figure 6.7 shows a block diagram of the cold start-up/warm start-up determine function. Figure 6.8 shows

its operation exmaple.

Program running started

Pch transistor ON (Approx. 4V)

CPU reset release

Set to "1" by program

The WDC5 bit is set to "0"

as soon as enough voltage

is applied to VCC.

T > 100

µs

"1"

"0"

VCC

WDC5 Bit

RESET

Reset Sequence (Approx. 20

µs @16MHz)

NOTES:

1. Time difference between T1 and T2 may affect the WDC5 bit setting period.

No change

even if the

voltage applied

to RESET is 0V.

Hardware Reset 1 when Power-on

Write to WDC register

COLD/WARM

WDC5 Bit

(Cold Start-up/Warm Start-up)

Figure 6.7

Cold Start-up/Warm Start-up Determine Function Block Diagram

Figure 6.8 Cold Start-up/Warm Start-up Determine Function Operation

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