R8C datasheet(68/199 Pages) RENESAS

68 / 199 page

R8C/10 Group

Rev.1.20 Jan 27, 2006

page 58 of 180

REJ09B0019-0120

12.1.1 Timer Mode

In this mode, the timer counts an internally generated count source (See “Table 12.2 Timer Mode

Specifications”). Figure 12.4 shows the TXMR register in timer mode.

Item

Specification

Count source

f1, f2, f8, f32

Count operation

• Down-count

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

is continued

Divide ratio

1/(n+1)(m+1)

n: set value of PREX register, m: set value of TX register

Count start condition

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

Count stop condition

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

Interrupt request generation timing When Timer X underflows [Timer X interruption]

INT1/CNTR0 pin function

Programmable I/O port, or INT1 interrupt input

CNTR0 pin function

Programmable I/O port

Read from timer

Count value can be read by reading TX register

Same applies to PREX register.

Write to timer

Value written to TX register is written to both reload register and counter.

Same applies to PREX register.

Table 12.2 Timer Mode Specifications

Figure 12.4 TXMR Register in Timer Mode

12.1 Timer (Timer X)

Timer X mode register

SymbolAddressAfter reset

TXMR008B16

0016

Bit name

Function

Bit symbol

b7 b6 b5 b4 b3 b2 b1 b0

0 0 : Timer mode or pulse period

measurement mode

b1 b0

TXMOD2

TXS

TXMOD1

R0EDG

TXMOD0

TXOCNT

Operation mode

select bit 0, 1

Timer X count

start flag

0 : Stops counting

1 : Starts counting

Operation mode

select bit 2

Set to "0" in timer mode

0 : Rising edge

1 : Falling edge

TXEDG

TXUND

INT1/CNTR0 polarity

switching bit(1, 2)

Set to "0" in timer mode

0 : Other than pulse period measurement mode

NOTES:

1. The IR bit in the INT1IC register may be set to “1” (interrupt requested) when the R0EDG bit is rewritten.

Refer to the paragraph 19.2.5 “Changing Interrupt Factor” in the Usage Notes Reference Book.

2. This bit is used to select the polarity of INT1 interrupt in timer mode.

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