M16C26 Datasheet, PDF (71/239 Pages) Renesas Technology Corp – 16-BIT CMOS SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/20 SERIES

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Preliminary Specifications Rev. 0.9
Specifications in this manual are tentative
Watchdog Timer
and
subject to change.
SINGLE-CHIP 16-BIT
M16C/26 Group
CMOS MICROCOMPUTER
BCLK
HOLD
Write to the watchdog timer
start register
(address 000E16)
Prescaler
1/16
CM07 = 0
WDC7 = 0
1/128
CM07 = 0
WDC7 = 1
CM07 = 1
1/2
RESET
Watchdog timer
Set to
7FFF16
Figure 1.10.1. Block diagram of watchdog timer
PM12 = 0
Watchdog timer
interrupt request
Reset
PM12 = 1
Watchdog timer control register
b7 b6 b5 b4 b3 b2 b1 b0
0
Symbol
WDC
Address
After reset
000F16 00?XXXXX 2(Note1)
Bit symbol
Bit name
Function
RW
High-order bit of watchdog timer
RO
WDC5
Cold start / warm start
0 : Cold start
discrimination flag (Note 2) 1 : Warm start
RW
Reserved bit
Set to 0
RW
WDC7 Prescaler select bit
0 : Divided by 16
1 : Divided by 128
RW
Note 1: The WDC5 bit is set to 0 immediately after power-on (cold start).
Note 2: The WDC5 bit will always be set to a 1 whenever the WDC SFR is written (regardless of value of WDC5 bit).
Watchdog timer start register
b7
b0
Symbol
Address When reset
WDTS
000E16 Indeterminate
Function
RW
The watchdog timer is initialized and starts counting after a write instruction to
this register. The watchdog timer value is always initialized to 7FFF16
regardless of whatever value is written.
Figure 1.10.2. Watchdog timer control and start registers
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Renesas Technology Corp.