M16CSLASH26 datasheet(97/239 Pages) RENESAS

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Renesas Technology Corp.

Timer B

M16C/26 Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Under

development

Preliminary Specifications Rev. 0.9

Specifications in this manual are tentative and subject to change.

Item

Specification

Count source

• External signals input to TBiIN pin

• Effective edge of count source can be a rising edge, a falling edge, or falling

and rising edges as selected by software

Count operation

• Counts down

• When the timer underflows, it reloads the reload register contents before

continuing counting

Divide ratio

1/(n+1)

n : Set value

Count start condition

Count start flag is set (= 1)

Count stop condition

Count start flag is reset (= 0)

Interrupt request generation timing The timer underflows

TBiIN pin function

Count source input

Read from timer

Count value can be read out by reading timer Bi register

Write to timer

• When counting stopped

When a value is written to timer Bi register, it is written to both reload register

and counter

• When counting in progress

When a value is written to timer Bi register, it is written to only reload register

(Transferred to counter at next reload time)

(2) Event counter mode

In this mode, the timer counts an external signal or an internal timer's overflow. (See Table 1.13.7.)

Figure 1.13.20 shows the timer Bi mode register in event counter mode.

Table 1.13.7. Timer specifications in event counter mode

Figure 1.13.20. Timer Bi mode register in event counter mode

Timer Bi mode register

Symbol

Address

When reset

TBiMR(i=0 to 2)

039B16 to 039D16

00XX00002

Bit name

Function

Bit symbol

Operation mode select bit

0 1 : Event counter mode

b1 b0

TMOD1

TMOD0

MR0

Count polarity select

bit (Note 1)

MR2

MR1

MR3

Invalid in event counter mode.

In an attempt to write to this bit, write 0 . The value, if read in

event counter mode, turns out to be indeterminate.

TCK1

TCK0

0 0 : Counts external signal's

falling edges

0 1 : Counts external signal's

rising edges

1 0 : Counts external signal's

falling and rising edges

1 1 : Must not be set.

b3 b2

Nothing is assigned (i = 1, 2)

In an attempt to write to this bit, write 0 . The value, if read,

turns out to be indeterminate.

Note 1: Valid only when input from the TBiIN pin is selected as the event clock.

If timer's overflow is selected, this bit can be 0 or 1 .

Note 2: Timer B0.

Note 3: Timer B1, timer B2.

Note 4: Set the corresponding port direction register to 0 .

Invalid in event counter mode.

Can be 0 or 1 .

Event clock select

0 : Input from TBiIN pin (Note 4)

1 : TBj overflow

(j = i

1; however, j = 2 when i = 0)

0 (Must always be 0 in event counter mode; i = 0)

(Note 2)

(Note 3)

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