r8a77850anbg Renesas Electronics Corporation., r8a77850anbg Datasheet - Page 803

• Manufacturer Part Number: r8a77850anbg
• Description: Renesas 32-bit Risc Microcomputer Superh? Risc Engine Family
• Manufacturer: Renesas Electronics Corporation.

WDTBCNT is an 18-bit counter that is incremented by the peripheral clock. If the period of
peripheral clock Pck is represented as tPck (ns), the overflow time of WDTBCNT is expressed as
follows.
WDTCNT is a 12-bit counter that is incremented each time WDTBCNT overflows. The time until
WDTCNT overflows becomes maximum when 0 is written to all the bits in WDTST. If the period
of peripheral clock Pck is represented as tPck (ns), the maximum overflow time of WDTCNT is
expressed as follows.
The time until WDTCNT overflows becomes minimum when H'5A00 0001 is written to WDTST.
In this case, the overflow time is equal to that of WDTBCNT.
For example, if the peripheral clock frequency is 50 MHz, tPck is 20 ns and the overflow times are
as follows.
16.4.5
Setting the overflow value in WDTBST clears WDTBCNT to 0, and setting the overflow value in
WDTST clears WDTCNT to 0.
2
2
Overflow time of WDTBCNT: 0.262
Maximum overflow time of WDTCNT: 1.073
18
12
Clearing WDT Counters
[bit]
[bit]
×
× (
tPck [ns] = 0.262
0.262
×
tPck) [ms] = 1.073
×
tPck [ms]
×
×
20 = 5.24 [ms]
tPck [s]
×
20 = 21.46 [s]
Rev.1.00 Jan. 10, 2008 Page 773 of 1658
16. Watchdog Timer and Reset (WDT)
REJ09B0261-0100