M16C26A Datasheet, PDF (122/352 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/Tiny SERIES

M16C/26A Group (M16C/26A, M16C/26B, M16C/26T)
12. Timer
12.1.4. Pulse Width Modulation (PWM) Mode
In PWM mode, the timer outputs pulses of a given width in succession (see Table 12.1.4.1). The counter
functions as either 16-bit pulse width modulator or 8-bit pulse width modulator. Figure 12.1.4.1 shows
TAiMR register in pulse width modulation mode. Figures 12.1.4.2 and 12.1.4.3 show examples of how a
16-bit pulse width modulator operates and how an 8-bit pulse width modulator operates.
Table 12.1.4.1. Specifications in Pulse Width Modulation 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
Specification
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 n : set value of TAi register (i=o to 4)
• Cycle time (2¹⁶-1) / fj fixed fj: count source frequency (f1, f2, f8, f32, fC32)
• High level width n x (m+1) / fj n : set value of TAi register high-order address
• Cycle time (2⁸-1) x (m+1) / fj m : set value of TAi register low-order address
• TAiS bit in theTABSR register is set to “1” (= start counting)
• The TAiS bit is set to "1" and external trigger input from the TAiIN pin
• The TAiS bit is set to "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)
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)
Rev. 2.00 Feb.15, 2007 page 105 of 329
REJ09B0202-0200