Operations; Operation As Watch Timer; Operation As Interval Timer; Table 10-3: Interval Time Of Interval Timer - NEC V850E/CA1 ATOMIC Preliminary User's Manual

10.4 Operations

10.4.1 Operation as watch timer

The watch timer operates with time intervals from 2.09715 s to 512 µs
7812.5 Hz.
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 control register (WTM) are set to 1. When these bits are cleared to 0, the 11-bit prescaler and 5-
bit counter are cleared, and the watch timer stops the count operation.
When the interval timer function is started at the same time, the watch timer can be started from 0 sec-
ond by resetting WTM1 to 0. However, an error of up to 2.09715 s to 512 µs may occur when the watch
timer overflows (INTWT).
Notes: 1. f = 4 MHz with fw of 31250 Hz [f
SUB
2. f = 5 MHz with fw of 39062.5 Hz [f
SUB

10.4.2 Operation as interval timer

The watch timer can also be used as an interval timer that repeatedly generates an interrupt at intervals
specified by a count value set in advance.
The interval time can be selected by bits 4 through 6 (WTM4 through WTM6) of the watch timer mode
control register (WTM).
WTM6 WTM5
0 0
0 0
0 1
0 1
1 0
1 0
1 1
1 1
Note: f = 4 MHz
SUB
Remark: fw: Watch timer clock frequency
Chapter 10 Watch Timer

Table 10-3: Interval Time of Interval Timer

WTM4 Interval Time
0 4
2 × 1/f
1 5
2 × 1/f
0 6
2 × 1/f
1 7
2 × 1/f
0
8
2 × 1/f
1 9
2 × 1/f
0
10
2 × 1/f
1 11
2 × 1/f
Preliminary User's Manual U14913EE1V0UM00
] / 7812.5 Hz [f
CKSEL1
] / 9765.625 Hz [f
CKSEL1
f
fw =
CKSEL2
2.408 ms
W
4.096 ms
W
8.192 ms
W
16.384 ms
W
32.768 ms
W
65.536 ms
W
131.072 ms
W
262.144 ms
W
Note
with fw of 31250 Hz /
]
CKSEL2
]
CKSEL2
Note
f
fw =
CKSEL1
512 µs
1.024 ms
2.048 ms
4.096 ms
8.192 ms
16.384 ms
32.768 ms
65.536 ms
Note
303