Timers (Timer A)
120
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
development
Preliminary Specifications Rev.1.0
Specifications in this manual are tentative and subject to change.
4. Pulse Width Modulation (PWM) Mode
In PWM mode, the timer outputs pulses of a given width in succession (see Table 1.14.5). The counter
functions as either 16-bit pulse width modulator or 8-bit pulse width modulator. Figure 1.14.13 shows
TAiMR register in pulse width modulation mode. Figures 1.14.14 and 1.14.15 show examples of how a
16-bit pulse width modulator operates and how an 8-bit pulse width modulator operates.
Table 1.14.5. Specifications in PWM Mode
Item
Specification
Count source
Count operation
f
1
, f
2
, f
8
, f
32
, f
C32
D
own-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
n : set value of TAi register (i=o to 4)
Cycle time (2
16
-1) / fj fixed fj: count source frequency (f
1
, f
2
, f
8
, f
32
, f
C32
)
High level width n x (m+1) / fj n : set value of TAiMR register high-order address
Cycle time (2
8
-1) x (m+1) / fj m : set value of TAiMR register low-order address
External trigger input from the TAi
IN
pin
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 of TABSR register is set to “1” (= start counting)
TAiS bit is set to “0” (= stop counting)
PWM pulse goes “L”
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)
16-bit PWM
8-bit PWM
Count start condition
Count stop condition
Interrupt request generation timing
TAi
IN
pin function
TAi
OUT
pin function
Read from timer
Write to timer