7540 datasheet(138/366 Pages) RENESAS

138 / 366 page

2-62

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

APPLICATION

7540 Group

2.4 Timer X

2.4.7 Notes on timer X

Notes on using each mode of timer X are described below.

(1) Count source

➀ f(XIN) can be used only when a ceramic oscillator or an on-chip oscillator is used.

Do not use f(XIN) at RC oscillation.

(2) Pulse output mode

➀ In order to use CNTR0 pin, set “1” to bit 4 of the port P1 direction register (output mode).

➁ In order to use TXOUT pin, set “1” to bit 3 of the port P0 direction register (output mode).

➂ CNTR0 interrupt active edge depends on the CNTR0 active edge switch bit. When this bit is “0”,

the CNTR0 interrupt request bit is set to “1” at the falling edge of CNTR0 pin input signal. When

this bit is “1”, the CNTR0 interrupt request bit is set to “1” at the rising edge of CNTR0 pin input

signal.

(3) Pulse width measurement mode

➀ In order to use CNTR0 pin, set “1” to bit 4 of the port P1 direction register (output mode).

➁ CNTR0 interrupt active edge depends on the CNTR0 active edge switch bit. When this bit is “0”,

the CNTR0 interrupt request bit is set to “1” at the falling edge of CNTR0 pin input signal. When

this bit is “1”, the CNTR0 interrupt request bit is set to “1” at the rising edge of CNTR0 pin input

signal.

7540 Datasheet(PDF) 138 Page - Renesas Technology Corp