Renesas 6NM User Manual

Rev.1.10    Jul 01, 2005    page 106 of 318
REJ09B0124-0110

M16C/6N Group (M16C/6NK, M16C/6NM)

12. Timers

This document is under development and its contents are subject to change.

In pulse width modulation mode, the timer outputs pulses of a given width in succession. The counter

functions as either 16-bit pulse width modulator or 8-bit pulse width modulator.

Table 12.5 lists specifications in pulse width modulation mode. Figure 12.12 shows TAiMR register in

pulse width modulation mode.

Figures 12.13 and 12.14 show examples of how a 16-bit pulse width modulator operates and how an 8-bit

pulse width modulator operates, respectively.

Item

Specification

Count Source

f1, f2, f8, f32, fC32

Count Operation

• 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

16-bit PWM

• High level width   n / fj

n : set value of the TAi register

• Cycle time (2

16

-1) / fj fixed

fj : count source frequency (f1, f2, f8, f32, fC32)

8-bit PWM

• High level width  n 

✕ (m+1) / fj n : set value of the TAi register high-order address

• Cycle time (2

8

-1) 

✕ (m+1) / fj m : set value of the TAi register low-order address

Count Start Condition

• The TAiS bit in the 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 overflow or underflow,

Timer Ak overflow or underflow

Count Stop Condition

The TAiS bit is set to “0” (stop counting)

Interrupt Request Generation Timing On the falling edge of the PWM pulse

TAiIN Pin Function

I/O port or trigger input

TAiOUT Pin Function

Pulse output

Read from Timer

An indeterminate value is read by reading the TAi register

Write to Timer

• When not counting and until the 1st count source is input after counting start

Value written to the TAi register is written to both reload register and counter

• When counting (after 1st count source input)

Value written to the TAi register is written to only reload register

(Transferred to counter when reloaded next)

 i = 0 to 4

j = i - 1, except j = 4 if i = 0

k = i + 1, except k = 0 if i = 4