R8CSLASH15 datasheet(104/277 Pages) RENESAS

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R8C/14 Group, R8C/15 Group

13. Timers

Rev.2.10

Jan 19, 2006

Page 92 of 253

REJ09B0164-0210

13.1.4

Pulse Width Measurement Mode

Pulse width measurement mode is mode to measure the pulse width of an external signal which

inputs from the INT1/CNTR0 pin (See Table 13.5 Specification of Pulse Width Measurement

Mode). Figure 13.7 shows the TXMR Register in Pulse Width Measurement Mode. Figure 13.8

shows an Operating Example in Pulse Width Measurement Mode.

Table 13.5

Specification of Pulse Width Measurement Mode

Item

Specification

Count Source

f1, f2, f8, fRING

Count Operation

• Decrement

• Continuously counts the selected signal only when the measurement pulse is

“H” level, or conversely only “L” level.

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

and the count is inherited

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]

• Rising or falling of the CNTR0 input (end of measurement period) [INT1

interrupt]

INT10/CNTR00,

INT11/CNTR01 Pin

Function

Measurement pulse input (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.

Select Function

•INT1/CNTR0 signal polarity switch function

The R0EDG bit can select during “H” or “L” level as the input pulse

measurement

• Measurement pulse input pin select function

The CNTRSEL bit in the UCON register can select the CNTR00 or CNTR01

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