M16C6S_09 Datasheet, PDF (89/208 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6S Group
Timer A
4. Pulse Width Modulation (PWM) Mode
In PWM mode, the timer outputs pulses of a given width in succession (see Table 1.12.5). The counter
functions as either 16-bit pulse width modulator or 8-bit pulse width modulator. Figure 1.12.10 shows
TAiMR register in pulse width modulation mode. Figures 1.12.11 and 1.12.12 show examples of how a
16-bit pulse width modulator operates and how an 8-bit pulse width modulator operates.
Table 1.12.5. Specifications in PWM Mode
Item
Specification
Count source
Count operation
16-bit PWM
8-bit PWM
f1, f2, f8, f32
• 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 n : set value of TAi register (i=o to 4)
• Cycle time (2¹⁶-1) / fj fixed fj: count source frequency (f1, f2, f8, f32)
• High level width n x (m+1) / fj n : set value of TAiMR register high-order address
• Cycle time (2⁸-1) x (m+1) / fj m : set value of TAiMR register low-order address
Count start condition
• 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 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
Count stop condition
TAiS bit is set to “0” (= stop counting)
Interrupt request generation timing PWM pulse goes “L”
TAiIN pin function
I/O port or trigger input
TAiOUT pin function
Pulse output
Read from timer
An indeterminate value is read by reading TAi register
Write to timer
• 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)
Rev.5.01 Dec 10, 2009 page 89 of 201
REJ03B0014-0501