Renesas M16C FAMILY, Руководство пользователя

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Rev.2.00 Oct 16, 2006 page 299 of 354
REJ09B0340-0200
M30245 Group 3. Timer A Applications
In this process, Timer A0 and A1 are used to generate variable-period, variable-duty PWM out-
put. Figure 3.2.1 shows the operation timing, Figure 3.2.2 shows the connection diagram, and
Figures 3.2.3 and 3.2.4 show the set-up procedure.
Use the following peripheral functions:
• Timer mode of timer A
• One-shot timer mode of timer A
(1) Set timer A0 in timer mode, and set timer A1 in one-shot timer mode with pulse-output function.
(2) Set 1 ms, the PWM period, to timer A0. Set 500 µs, the width of PWM “H” pulse, to timer A1.
Both timer A0 and timer A1 use f
1
for the count source.
(3) Connect a 16-MHz oscillator to X
IN
.
(1) Setting the count start flag to “1” causes the counter of timer A0 to begin counting. The
counter of timer A0 performs a down count on count source f
1
.
(2) If the counter of timer A0 underflows, the counter reloads the content of the reload register
and continues counting. At this time, the timer A0 interrupt request bit goes to “1”.
(3) An underflow in timer A0 triggers the counter of timer A1 and causes it to begin counting. When
the counter of timer A1 begins counting, the output level of the TA1
OUT
pin goes to “H”.
(4) As soon as the count of the counter of timer A1 becomes “0000
16
”, the output level of TA1
OUT
pin goes to “L”, and the counter reloads the content of the reload register and stops counting.
At the same time, the timer A1 interrupt request bit goes to “1”.
3.2 Variable-Period Variable-Duty PWM Output
Overview
Specifications
Operation