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M16C/62P Group (M16C/62P, M16C/62PT)
15.1.4
Pulse Width Modulation (PWM) Mode
In PWM mode, the timer outputs pulses of a given width in succession (see Table 15.5). The counter functions
as either 16-bit pulse width modulator or 8-bit pulse width modulator. Figure 15.13 shows TAiMR Register in
PWM Mode. Figures 15.14 and 15.15 show Example of 16-bit Pulse Width Modulator Operation and Example
of 8-bit Pulse Width Modulator Operation.
Table 15.5
Specifications in PWM Mode
Item
Count Source
Count Operation
16-bit PWM
8-bit PWM
Count Start Condition
Count Stop Condition
Interrupt Request
Generation Timing
TAiIN Pin Function
TAiOUT Pin Function
Read from Timer
Write to Timer
Rev.2.41
Jan 10, 2006
REJ09B0185-0241
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f1, f2, f8, f32, fC32
• Down-count (operating as an 8-bit or a 16-bit pulse width modulator)
• The timer reloads a new value at a rising edge of PWM pulse and continues
counting
• The timer is not affected by a trigger that occurs during counting
• High level width n / fj
16
• Cycle time (2
-1) / fj fixed
• High level width n × (m+1) / fj n : set value of TAi register high-order address
8
-1) × (m+1) / fj m : set value of TAi register low-order address
• Cycle time (2
• TAiS bit of TABSR register is set to "1" (= start counting)
• The TAiS bit = 1 and external trigger input from the TAiIN pin
• The TAiS bit = 1 and one of the following external triggers occurs
• Timer B2 overflow or underflow,
Timer Aj (j=i-1, except j=4 if i=0) overflow or underflow,
Timer Ak (k=i+1, except k=0 if i=4) overflow or underflow
TAiS bit is set to "0" (= stop counting)
On the falling edge of PWM pulse
I/O port or trigger input
Pulse output
An indeterminate value is read by reading TAi register
• When not counting and until the 1st count source is input after counting start
Value written to TAi register is written to both reload register and counter
• When counting (after 1st count source input)
Value written to TAi register is written to only reload register
(Transferred to counter when reloaded next)
Page 153 of 390
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Specification
n : set value of TAi register (i=o to 4)
fj: count source frequency (f1, f2, f8, f32, fC32)
010-62245566 13810019655
15. Timers
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