M32CSLASH8B datasheet(180/406 Pages) RENESAS

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M32C/8B Group

15. Timer A

Preliminary specification

Specifications in this manual are tentative and subject to change.

REJ09B0450-0050 Rev.0.50 Oct 31, 2008

Page 163 of 385

15.1.4

Pulse Width Modulation Mode

In pulse width modulation mode, the timer outputs pulse signals of a given width repeatedly. The counter

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

Table 15.7 lists specifications of pulse width modulation mode. Figures 15.19 and 15.20 show examples of a

16-bit pulse width modulator and 8-bit pulse width modulator operations.

Table 15.7

Specifications of Pulse Width Modulation Mode

NOTES:

1. Bits CNT3 to CNT0 in the TCSPR register select no division (n = 0) or divide-by-2n (n = 1 to 15).

2. Wait for one or more count source cycles to write after the count starts.

Item

Specification

Count source

f1, f8, f2n(1), fC32

Count operation

• Counter decrements

(The counter functions as the 8-bit or 16-bit pulse width modulator.)

The contents of the reload register are reloaded at the rising edge of the PWM

pulse and the count continues. The count continues without reloading even

if the re-trigger occurs while counting.

16-bit PWM

• “H” width = n / fj

n: setting value of the TAi register (i = 0 to 4), 0000h to FFFEh

fj: count source frequency

•Cycle = (216 - 1) / fj

The cycle is fixed to this value

8-bit PWM

• “H” width = n x (m + 1) / fj

•Cycle = (28 - 1) x (m + 1) / fj

m: setting value of low-order bit address of the TAi register, 00h to FFh

n: setting value of high-order bit address of the TAi register, 00h to FEh

Count start condition

When a trigger is not used (the MR2 bit in the TAiMR register is 0):

Set the TAiS bit in the TABSR register to 1

When a trigger is used (the MR2 bit in the TAiMR register is 1):

A trigger, selectable from the following occurs while the TAiS bit in the TABSR

• an external trigger is applied to TAiIN pin

• timer B2 overflows or underflows

• timer Aj overflows or underflows (j = i - 1, except j = 4 if i = 0)

• timer Ak overflows or underflows (k = i + 1, except k = 0 if i = 4)

Count stop condition

The TAiS bit is set to 0 (count stops)

Interrupt request generation timing At the falling edge of the PWM pulse

TAiIN pin function

Trigger input

TAiOUT pin function

Pulse output

Read from timer

A read from the TAi register returns undefined value

Write to timer

• A write to the TAi register while the count is stopped:

The value is written to both the reload register and the counter.

• A write to the TAi register while counting:

The value is written to the reload register (It is transferred to the counter at the

next reload timing).(2)

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