R8CSLASH15 datasheet(99/277 Pages) RENESAS

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R8C/14 Group, R8C/15 Group

13. Timers

Rev.2.10

Jan 19, 2006

Page 87 of 253

REJ09B0164-0210

13.1.1

Timer Mode

Timer mode is mode to count the count source which is internally generated (See Table 13.2

Specification of Timer Mode). Figure 13.4 shows the TXMR Register in Timer Mode.

Figure 13.4

TXMR Register in Timer Mode

Table 13.2

Specification of Timer Mode

Item

Specification

Count Source

f1, f2, f8, fRING

Count Operation

• Decrement

• When the timer underflows, the contents in the reload register is reloaded and

the count is inherited

Divide Ratio

1/(n+1)(m+1) n: setting value of PREX register, m: setting value of TX register

Count Start Condition

Write “1” (count starts) to the TXS bit in the TXMR register

Count Stop Condition

Write “0” (count stops) to the TXS bit in the TXMR register

Interrupt Request

Generation Timing

When Timer X underflows [Timer X interrupt]

INT10/CNTR00,

INT11/CNTR01 Pin

Function

Programmable I/O port, or INT1 interrupt input

CNTR0 Pin Function

Programmable I/O port

Read from Timer

The count value can be read by reading the TX and PREX registers

Write to Timer

• When writing to the TX and PREX registers while the count stops, the value is

written to both the reload register and counter.

• When writing to the TX and PREX registers during the count, the value is

written to each reload register of the TX and PREX registers at the following

count source input and the data is transferred to the counter at the second

count source input and the count re-starts at the third count source input.

Timer X Mode Register

Symbol

Address

After Reset

TXMR

008Bh

00h

Bit Symbol

Bit Name

Function

INT1

_____

/CNTR0 Signal

Polarity Sw itch Bit(1, 2)

NOTES :

3. Refer to 20.4.2 Tim er X for precautions on the TXS bit.

The IR bit in the INT1IC register may be set to “1” (requests interrupt) w hen the R0EDG bit is rew ritten.

Refer to 20.2.5 Changing Interrupt Factor.

R0EDG

TXOCNT

TXMOD2

This bit is used to select the polarity of INT1

_____

interrupt in timer mode.

Set to “0” in timer mode

TXMOD0

Operating Mode Select Bit 0, 1

b1 b0

0 0 : Timer mode or pulse period measurement

mode

TXMOD1

b7 b6 b5 b4

0000 0

b3 b2

0 : Rising edge

1 : Falling edge

TXS

Timer X Count Start Flag(3)

0 : Stops counting

1 : Starts counting

b1 b0

TXUND

TXEDG

Set to “0” in timer mode

Operating Mode Select Bit 2

0 : Other than pulse period measurement mode

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