R8CSLASH20 datasheet(136/501 Pages) RENESAS

136 / 501 page

R8C/20 Group, R8C/21 Group

14. Timers

Rev.2.00 Aug 27, 2008

Page 120 of 458

REJ09B0250-0200

14.1

Timer RA

Timer RA is an 8-bit timer with an 8-bit prescaler.

The prescaler and timer consist of the reload register and counter. The reload register and counter are allocated at

the same address. When accessing the TRAPRE and TRA registers, the reload register and counter can be accessed

(refer to Table 14.2 to 14.6 the Specification of Each Modes).

The count source for timer RA is the operating clock that regulates the timing of timer operations such as counting

and reloading.

Figure 14.1 shows the Block Diagram of Timer RA. Figures 14.2 to 14.4 show the registers associated with Timer

RA.

Timer RA contains five operation modes listed as follows:

• Timer mode:

The timer counts an internal count source.

• Pulse output mode:

The timer counts an internal count source and outputs the pulses which

invert the polarity by underflow of the timer.

• Event counter mode:

The timer counts external pulses.

• Pulse width measurement mode: The timer measures the pulse width of an external pulse.

• Pulse period measurement mode: The timer measures the pulse period of an external pulse.

Figure 14.1

Block Diagram of Timer RA

TCSTF

bit

TCKCUT

bit

= 000b

= 001b

= 011b

= 010b

fOCO

TCK2 to TCK0 bit

Counter

Reload

TRAPRE register

(Prescaler)

Peripheral data bus

Timer RA interrupt

Write to TRAMR register

Write to TSTOP bit 1

TCSTF, TSTOP: TRACR register

TEDGSEL, TOPCR, TOENA, TIOSEL, TIPF1, TIPF0: TRAIOC register

TMOD2 to TMOD0, TCK2 to TCK0, TCKCUT: TRAMR register

Toggle flip-flop

CLR

TOENA bit

TRAO pin

INT1/TRAIO (P1-5) pin

TMOD2 to TMOD0

= 011b or 100b

Polarity

switching

Digital

filter

Counter

Reload

TRA register

(Timer)

TIPF1 to TIPF0 bit

= 00b

= 10b

= 11b

f32

TIOSEL = 0

TIOSEL = 1

Count control

circle

TMOD2 to TMOD0 = 001b

TOPCR bit

Underflow signal

Measurement completion signal

TIPF1 to

TIPF0 bit

= Except 00b

= 00b

INT1/TRAIO (P1-7) pin

TEDGSEL = 1

TEDGSEL = 0

TMOD2 to TMOD0

= Except 010b

TMOD2 to TMOD0

= 010b

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