7540 datasheet(176/366 Pages) RENESAS

176 / 366 page

2-100

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

APPLICATION

7540 Group

2.5 Timer Y and timer Z

➂ The waveform extension function by the timer Z waveform extension control bits can be used only

when “0016” is set to Prescaler Z.

When the value other than “0016” is set to Prescaler Z, be sure to set “0” to EXPZP. Also, when

the timer Y underflow is selected as the timer Z count source, the waveform extension function

cannot be used.

An example of a measurement is shown below.

ex.) The underflow of timer is stored by polling etc. using timer Z interrupt.

Writing to primary is performed in by judging that there is no problem if the underflow by

secondary is completed with reference to primary write operation before.

(Depending on a primary setting value, primary write timing, software and timing of external

trigger to INT0 pin, it may be impossible.)

➃ When using this mode, be sure to set “1” to the timer Z write control bit to select “write to latch

only”.

➄ In order to use TZOUT pin, set “1” to bit 2 of the port P0 direction register (output mode).

➅ Stop Timer Z to change the INT0 pin one-shot trigger control bit and INT0 pin one-shot trigger

active edge selection bit.

(4) Programmable wait one-shot generation mode (timer Z)

➀ In the programmable wait one-shot generation mode, values of TZS, EXPZP and EXPZS are valid

by writing to TZP. Even when changing TZP is not required, write the same value again.

An example of a measurement is shown below.

ex.) The underflow by the primary and the underflow by secondary are stored by polling etc. using

timer Z interrupt.

Writing to primary is performed in by judging that there is no problem if the underflow by

secondary is completed with reference to primary write operation before.

(Depending on a primary setting value, primary write timing, software and timing of external

trigger to INT0 pin, it may be impossible.)

➁ In the programmable wait one-shot generation mode, when the setting value is changed while the

waveform is output, set by software in order not to execute the writing to TZP and the timing of

timer underflow during the secondary interval simultaneously.

➂ The waveform extension function by the timer Z waveform extension control bit can be used only

when “0016” is set to Prescaler Z.

When the value other than “0016” is set to Prescaler Z, be sure to set “0” to EXPZP and EXPZS.

Also, when the timer Y underflow is selected as the timer Z count source, the waveform extension

function cannot be used.

➃ When using this mode, be sure to set “1” to the timer Z write control bits to select “write to latch

only”.

➄ When TZS is read out, the undefined value is read out. However, while Timer Z counts the setting

value of TZS (during one-shot output), the count value during the secondary interval can be

obtained by reading TZP.

➅ In order to use TZOUT pin, set “1” to bit 2 of the port P0 direction register (output mode).

➆ Stop Timer Z to change the INT0 pin one-shot trigger control bit and INT0 pin one-shot trigger

active edge selection bit.

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