M16CSLASH26 datasheet(88/239 Pages) RENESAS

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Renesas Technology Corp.

Timer A

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 TAiIN pin (effective edge can be selected by software)

• TB2 overflow, TAj overflow

Count operation

• Up count or down count can be selected by external signal or software

• When the timer overflows or underflows, it reloads the reload register con

tents before continuing counting (Note)

Divide ratio

1/ (FFFF16 - n + 1) for up count

1/ (n + 1) for down count

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 overflows or underflows

TAiIN pin function

Programmable I/O port or count source input

TAiOUT pin function

Programmable I/O port, pulse output, or up/down count select input

Read from timer

Count value can be read out by reading timer Ai register

Write to timer

• When counting stopped

When a value is written to timer Ai register, it is written to both reload register and counter

• When counting in progress

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

(Transferred to counter at next reload time)

Select function

• Free-run count function

Even when the timer overflows or underflows, the reload register content is not reloaded to it

• Pulse output function

Each time the timer overflows or underflows, the TAiOUT pin’s polarity is reversed

Note: This does not apply when the free-run function is selected.

Event Counter Mode

In this mode, the timer counts an external signal or an internal timer’s overflow. Timers A0 and A1 can

count a single-phase external signal. Timers A2, A3, and A4 can count a single-phase and a two-

phase external signal. Table 1.12.2 lists timer specifications when counting a single-phase external

signal. Figure 1.12.8 shows the timer Ai mode register in event counter mode.

Table 1.12.3 lists timer specifications when counting a two-phase external signal. Figure 1.12.9 shows

the timer Ai mode register in event counter mode.

Table 1.12.2. Timer specifications in event counter mode (when not processing two-phase pulse signal)

Figure 1.12.8. Timer Ai mode register in event counter mode

Note 1: In event counter mode, the count source is selected by the event / trigger select bit

(addresses 038216 and 038316).

Note 2: The settings of the corresponding port register and port direction register are invalid.

Note 3: Valid only when counting an external signal.

Note 4: When an L signal is input to the TAiOUT pin, the downcount is activated. When H ,

the upcount is activated. Set the corresponding port direction register to 0 .

Symbol

Address

When reset

TAiMR(i = 0 to 4) 039616 to 039A16

0016

Operation mode select bit

0 1 : Event counter mode (Note 1)

b1 b0

TMOD0

MR0

Pulse output function

select bit

0 : Pulse is not output

(TAiOUT pin is a normal port pin)

1 : Pulse is output (Note 2)

(TAiOUT pin is a pulse output pin)

Count polarity

select bit (Note 3)

MR2

MR1

MR3

0 (Must always be 0 in event counter mode)

TCK0

Count operation type

select bit

0 : Counts external signal's falling edge

1 : Counts external signal's rising edge

Up/down switching

cause select bit

0 : Up/down flag's content

1 : TAiOUT pin's input signal (Note 4)

0 : Reload type

1 : Free-run type

Bit symbol

Bit name

Function

TCK1

Invalid when not using two-phase pulse signal processing

Can be 0 or 1

TMOD1

Timer Ai mode register

(When not using two-phase pulse signal processing)

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