Panasonic MN101C77C, F77G user manual „Watchdog Timer Block Diagram, Block Diagram Watchdog Timer

Models: F77G MN101C77C

1 544
Download 544 pages 59.61 Kb
Page 314
Image 314

Chapter 9 Watchdog Timer

9-1 Overview

This LSI has a watchdog timer. This timer is used to detect software processing errors. It is controlled by the watchdog timer control register (WDCTR). And, once an overflow of watchdog timer is generated, a watchdog interrupt (WDIRQ) is generated. If the watchdog interrupt is generated twice, consecutively, it is regarded to be an indication that the software cannot execute in the intended sequence; thus, a system reset is initiated by the hardware.

9-1-1 Block Diagram

„Watchdog Timer Block Diagram

NRST

STOP

writeWDCTR

HALT fs

(sysclk)

DLYCTR

-

DLYS0

DLYS1

DLYS2

BUZS0

BUZS1

 

R

R

 

 

 

 

 

 

1/2~1/214

1/215~1/220

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

fs/214

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

fs/212

 

 

 

 

 

 

 

 

 

 

 

fs/210

 

 

 

 

 

 

 

 

 

 

 

 

fs/28

 

 

MUX

 

 

 

 

 

 

 

fs/26

 

 

 

 

 

 

 

 

 

 

 

 

 

fs/24

 

 

 

 

 

 

 

 

 

 

0

 

 

fs/22

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R

S

internal reset release

BUZS2

BUZOE

WDCTR

WDEN

WDTS0

WDTS1

WDTC0

WDTC1

WDTC2

-

-

fs/222

7fs/220 fs/218 fs/216

0

7

MUX

WDIRQ

Figure 9-1-1 Block Diagram (Watchdog Timer)

The watchdog timer is also used as a timer to count the oscillation stabilization wait time. This is used as a watchdog timer except at recovering from STOP mode and at reset releasing.

The watchdog timer is initialized at reset or at STOP mode, and counts system clock (fs) as a clock source from the initial value (x'0000'). The oscillation stabilization wait time is set by the oscillation stabilization control register (DLYCTR). After the oscillation stabilization wait, counting is continued as a

watchdog timer.

[

Chapter 2 2-8. Reset ]

IX - 2 Overview

Page 314
Image 314
Panasonic MN101C77C, F77G user manual „Watchdog Timer Block Diagram, Block Diagram Watchdog Timer