R8C2K datasheet(153/471 Pages) RENESAS

153 / 471 page

R8C/2K Group, R8C/2L Group

16. Timers

Rev.1.10

Dec 21, 2007

Page 136 of 450

REJ09B0406-0110

16.1

Timer RA

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

The prescaler and timer each consist of a reload register and counter. The reload register and counter are allocated

at the same address, and can be accessed when accessing registers TRAPRE and TRA (refer to Tables 16.2 to 16.6

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 16.1 shows a Block Diagram of Timer RA. Figures 16.2 and 16.3 show the registers associated with Timer

RA.

Timer RA contains the following five operating modes:

• Timer mode:

The timer counts the internal count source.

• Pulse output mode:

The timer counts the internal count source and outputs 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 16.1

Block Diagram of Timer RA

= 000b

= 001b

= 011b

= 010b

fOCO

TCK2 to TCK0 bit

TMOD2 to TMOD0

= other than 010b

Counter

Reload

TRAPRE register

(prescaler)

Data bus

Timer RA interrupt

Write to TRAMR register

Write 1 to TSTOP bit

TCSTF, TSTOP: TRACR register

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

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

Toggle

flip-flop

CLR

INT1/TRAIO (P1_5) pin

TCSTF bit

TCKCUT bit

TMOD2 to TMOD0

= 011b or 100b

TMOD2 to TMOD0

= 010b

Polarity

switching

Digital

filter

Counter

Reload

TRA register

(timer)

TIPF1 to TIPF0 bits

= 01b

= 10b

= 11b

f32

TIOSEL = 0

TIOSEL = 1

Count control

circle

TMOD2 to TMOD0 = 001b

TOPCR bit

Underflow signal

Measurement completion

signal

TIPF1 to TIPF0 bits

= other than

000b

= 00b

INT1/TRAIO (P1_7) pin

TEDGSEL = 1

TEDGSEL = 0

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