Datasheet

V850ES/JG3 CHAPTER 10 WATCH TIMER FUNCTIONS
R01UH0015EJ0300 Rev.3.00 Page 386 of 870
Sep 30, 2010
(1) Clock control
This block controls supplying and stopping the operating clock (f
X) when the watch timer operates on the main
clock.
(2) 3-bit prescaler
This prescaler divides f
X to generate fX/2, fX/4, or fX/8.
(3) 8-bit counter
This 8-bit counter counts the source clock (f
BGCS).
(4) 11-bit prescaler
This prescaler divides f
W to generate a clock of fW/2
4
to fW/2
11
.
(5) 5-bit counter
This counter counts f
W or fW/2
9
, and generates a watch timer interrupt request signal at intervals of 2
4
/fW, 2
5
/fW,
2
12
/fW, or 2
14
/fW.
(6) Selector
The watch timer has the following five selectors.
• Selector that selects one of f
X, fX/2, fX/4, or fX/8 as the source clock of the watch timer
• Selector that selects the main clock (f
X) or subclock (fXT) as the clock of the watch timer
• Selector that selects fW or fW/2
9
as the count clock frequency of the 5-bit counter
• Selector that selects 2
4
/fW, 2
13
/fW, 2
5
/fW, or 2
14
/fW as the INTWT signal generation time interval
• Selector that selects 2
4
/fW to 2
11
/fW as the interval timer interrupt request signal (INTWTI) generation time interval
(7) PRSCM register
This is an 8-bit compare register that sets the interval time.
(8) PRSM register
This register controls clock supply to the watch timer.
(9) WTM register
This is an 8-bit register that controls the operation of the watch timer/interval timer, and sets the interrupt request
signal generation interval.