R8CSLASH2G datasheet(174/344 Pages) RENESAS

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R8C/2G Group

17. Timers

Rev.1.00

Apr 04, 2008

Page 154 of 318

REJ09B0387-0100

17.1.4

Pulse Width Measurement Mode

In pulse width measurement mode, the pulse width of an external signal input to the INT1/TRAIO pin is

measured (refer to Table 17.5 Pulse Width Measurement Mode Specifications).

Figure 17.8 shows TRAIOC Register in Pulse Width Measurement Mode and Figure 17.9 shows an Operating

Example of Pulse Width Measurement Mode.

Table 17.5

Pulse Width Measurement Mode Specifications

Item

Specification

Count sources

f1, f2, f8, fOCO, fC32

Count operations

• Decrement

• Continuously counts the selected signal only when measurement pulse is “H”

level, or conversely only “L” level.

• When the timer underflows, the contents of the reload register are reloaded

and the count is continued.

Count start condition

1 (count starts) is written to the TSTART bit in the TRACR register.

Count stop conditions

• 0 (count stops) is written to the TSTART bit in the TRACR register.

• 1 (count forcibly stops) is written to the TSTOP bit in the TRACR register.

Interrupt request

generation timing

• When timer RA underflows [timer RA interrupt].

• Rising or falling of the TRAIO input (end of measurement period) [timer RA

interrupt]

INT1/TRAIO pin function Measured pulse input (INT1 interrupt input)

TRAO pin function

Programmable I/O port

Read from timer

The count value can be read by reading registers TRA and TRAPRE.

Write to timer

• When registers TRAPRE and TRA are written while the count is stopped,

values are written to both the reload register and counter.

• When registers TRAPRE and TRA are written during the count, values are

written to the reload register and counter (refer to 17.1.1.1 Timer Write

Control during Count Operation

Select functions

• Measurement level select

• The TEDGSEL bit in the TRAIOC register selects the “H” or “L” level period.

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