SAB80C515A-5 Datasheet, PDF (46/108 Pages) Siemens Semiconductor Group – 8-Bit CMOS Single-Chip Microcontroller Family

On-Chip Peripheral Components
Special Function Register WDTREL (Address 086H)
Bit No. _MSB
7
6
5
4
3
2
LSB
1
0
086H
Watchdog Timer Reload Register
WDTREL
Bit
WDTREL.7
WDTREL.6
to
WDTREL.0
Function
Prescaler select bit.
When set, the watchdog timer is clocked through an additional divide-by-16
prescaler (see figure 12).
Seven bit reload value for the high-byte of the watchdog timer.
This value is loaded to the WDT when a refresh is triggered by a consecutive
setting of bits WDT and SWDT.
Reset value of WDTREL is 00H.
Immediately after start (see next section for start procedure), the Watchdog Timer is initialized to
the reload value programmed to WDTREL.0-WDTREL.6. After an external HW reset (or power-on
reset, or HW Power Down) register WDTREL is cleared to 00H. The lower seven bits of WDTREL
can be loaded by software at any time.
Examples (given for 12 and 18 MHz oscillator frequency):
WDTREL
00H
80H
7FH
Time-out Period
f_OSC = 12 MHz f_OSC = 18 MHz
65.535 ms
43.690 ms
1.1 s
512 µs
0.73 s
341 µs
Comments
This is the default value and coincides
with the watchdog period of the SAB
80C515
maximum time period
minimum time period
Semiconductor Group
5-13