
165
Specifications in this manual are tentative and subject to change
Timer A
Mitsubishi microcomputers
M30240 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
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
the set-up procedure.
Table 2.11:
Timer A pulse width modulation mode, 16-bit PWM mode functions
Note:
j = i, but j = 4 when i = 0; k = j + 1 when i = 4
Operation
(1) If the TAiIN pin input level changes from “L” to “H” with the count start flag set to “1”, the counter
performs a down count on the count source. Also, the TAiOUT pin outputs an “H” level.
(2) The TAiOUT pin output level changes from “H” to “L” when a set time period elapses. At this time,
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 TAiOUT
outputs an “L” level.
Notes
The period of PWM pulses becomes (216 – 1)/fi, and the “H” level pulse width becomes n/fi. If the Timer Ai
register is set to “000016” the pulse width modulator does not work, and the TAiOUT pin output level remains
at “L”.
(fi: frequency of the count source f1, f8, f32; n: value of the timer)
Figure 2.25: Operation timing of pulse width modulation mode, 16-bit PWM mode selected
Item
Set-up
Count source
O
Internal count source (f1/f8/f32)
PWM mode
O
16-bit PWM
8-bit PWM
Count start condition
External trigger input (falling edge of input signal to the TAiIN pin)
O
External trigger input (rising edge of input signal to the TAiIN pin)
Timer overflow (TB2/TAj/TAk overflow)
Count source
TA iIN pin
input signal
PWM pulse output
from TA iOUT pin
Timer Ai interrupt
request bit
Count start flag
1 / fi X (2
1)
16
Conditions: Reload register = 000316, external trigger (rising edge of TAi IN pin input signal) is selected
Trigger is not generated by this signal
"H"
"L"
"1"
"0"
Cleared to "0" when interrupt request is
accepted, or cleared by software
1 / fi X n
"1"
"0"
Set to "1" by software
(1) Start count
(2) Output level "H" to "L"
Note: n = 000016 to FFFE16
(3) One period is complete
(4) Stop count
Cleared to "0"
by software