7540 datasheet(126/366 Pages) RENESAS

126 / 366 page

2-50

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

APPLICATION

7540 Group

2.4 Timer X

Fig. 2.4.13 Setting method for pulse output mode (1)

2.4.4 Pulse output mode

(1) Operation description

In the pulse output mode, the waveform whose polarity is inverted each time timer X underflows is

output from the P14/CNTR0 pin.

The output level of CNTR0 pin can be selected by the CNTR0 active edge switch bit. When the CNTR0

active edge switch bit is “0”, the output of CNTR0 pin is started at “H” level. When this bit is “1”, the

output is started at “L” level.

Also, the inverted waveform of pulse output from CNTR0 pin can be output from TXOUT pin by setting

“1” to the P03/TXOUT output valid bit.

When using a timer in this mode, set the port P14 and P03 direction registers to output mode.

Timer X can stop counting by setting “1” to the timer X count stop bit.

Also, when Timer X underflows, the timer X interrupt request bit is set to “1”.

(2) Pulse output mode setting method

Figure 2.4.13 and Figure 2.4.14 show the setting method for pulse output mode of timer X.

b7b0

Process 1: Disable timer X interrupt.

Interrupt control register 1 (ICON1) [Address 3E16]

Timer X interrupt disabled

Port P1 direction register (P1D) [Address 0316]

Set the P14/CNTR0 pin to the output mode

Process 3: Set the CNTR0 pin to the output mode.

Process 2: Set timer X mode register.

Timer X mode register (TXM) [Address 2B16]

Port P0 direction register (P0D) [Address 0116]

Set the P03/TXOUT pin to the output mode

Process 4: Set the TXOUT pin as the output mode when TXOUT output is valid.

Pulse output mode

CNTR0 active edge switch

0: Output is started at “H” level

1: Output is started at “L” level

Timer X count stop

P03/TXOUT output

0: Output invalid (I/O port)

1: Output valid (inverted CNTR0 output)

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