upd70f3017ay Renesas Electronics Corporation., upd70f3017ay Datasheet - Page 211

• Manufacturer Part Number: upd70f3017ay
• Description: V850/sa1tm 32-/16-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

8.4 Operation
8.4.1 Operation as watch timer
MHz).
control register (WTM) are set to 1. When these bits are cleared to 0, the 9-bit prescaler and 5-bit counter are
cleared, and the watch timer stops the count operation.
occur.
the same time, an error of up to 0.5 seconds may occur when the watch timer overflows (INTWT).
8.4.2 Operation as interval timer
by a count value set in advance.
register (WTM).
The watch timer operates at time intervals of 0.5 seconds with the subclock (32.768 kHz) or main clock (16.777
The watch timer generates an interrupt request at fixed time intervals.
The count operation of the watch timer is started when bits 0 (WTM0) and 1 (WTM1) of the watch timer mode
The watch timer clears the 5-bit counter by setting the WTM1 bit to 0. At this time, an error of up to 15.6 ms may
The interval timer can be cleared by setting the WTM0 bit to 0. However, because the 5-bit counter is cleared at
The watch timer can also be used as an interval timer that repeatedly generates an interrupt at intervals specified
The interval time can be selected by bits 4 through 6 (WTM4 through WTM6) of the watch timer mode control
Remark
f
W
Other than above
: Watch timer clock frequency
WTM6
0
0
0
0
1
1
WTM5
0
0
1
1
0
0
Table 8-3. Interval Time of Interval Timer
WTM4
0
1
0
1
0
1
CHAPTER 8 WATCH TIMER
User’s Manual U12768EJ4V1UD
Setting prohibited
Interval Time
2
2
2
2
2
2
4
5
6
7
8
9
× 1/f
× 1/f
× 1/f
× 1/f
× 1/f
× 1/f
W
W
W
W
W
W
f
W
= 32.768 kHz
1.95 ms
3.91 ms
7.81 ms
15.6 ms
488
977
µ
µ
s
s
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