Pulse Width Modulation Mode - 16-Bit Pwm Mode Selected - Renesas M16C Series User Manual

M30240 Group

2.2.2.10 Pulse width modulation mode - 16-bit PWM mode selected

In pulse width modulation mode, select functions from those listed in Table 2.11 . An example using the
indicated options is described below. Figure 2.25 shows the operation timing, and Figure 2.26 shows
the set-up procedure.
Table 2.11: Timer A pulse width modulation mode, 16-bit PWM mode functions
Item
Count source O
O
PWM mode
Count start condition
O
Note: j = i, but j = 4 when i = 0; k = j + 1 when i = 4
Operation
(1) If the TAi pin input level changes from "L" to "H" with the count start flag set to "1", the counter
IN
performs a down count on the count source. Also, the TAi
(2) The TAi pin output level changes from "H" to "L" when a set time period elapses. At this time,
OUT
the Timer Ai interrupt request bit goes to "1".
(3) The counter reloads the content of the reload register every time PWM pulses are output for one
cycle, and continues counting.
(4) Setting the count start flag to "0" causes the counter to hold its value and to stop. Also, the TAi
outputs an "L" level.
Notes
The period of PWM pulses becomes (2
register is set to "0000
at "L".
(fi: frequency of the count source f1, f8, f32; n: value of the timer)
Conditions: Reload register = 0003
Count source
TA pin
iIN
input signal
Count start flag
PWM pulse output
from TA
Timer Ai interrupt
request bit
Figure 2.25: Operation timing of pulse width modulation mode, 16-bit PWM mode selected
Rev.1.00 Sep 24, 2003 Page 165 of 360
Internal count source (f1/f8/f32)
16-bit PWM
8-bit PWM
External trigger input (falling edge of input signal to the TAi
External trigger input (rising edge of input signal to the TAi
Timer overflow (TB2/TAj/TAk overflow)
16
– 1)/fi, and the "H" level pulse width becomes n/fi. If the Timer Ai
" the pulse width modulator does not work, and the TAi
16
, external trigger (rising edge of TAi
16
1 / f
"H"
"L"
Trigger is not generated by this signal
Set to "1" by software
"1"
(1) Start count
"0"
(2) Output level "H" to "L"
"H"
pin
iOUT
"L"
"1"
"0"
Note: n = 0000 to FFFE
16 16
Set-up
pin outputs an "H" level.
OUT
pin input signal) is selected
IN
16
X (2 1)
i
Cleared to "0"
by software
(3) One period is complete
1 / f X n (4) Stop count
i
Cleared to "0" when interrupt request is
accepted, or cleared by software
Timer A
pin)
IN
pin)
IN
pin output level remains
OUT
OUT