7540 datasheet(49/88 Pages) RENESAS

49 / 88 page

7540 Group

Rev.4.00

Jun 21, 2004

page 49 of 82

REJ03B0011-0400Z

NOTES ON PERIPHERAL FUNCTIONS

s Interrupt

When setting the followings, the interrupt request bit may be set to “1”.

•When setting external interrupt active edge

Related register: Interrupt edge selection register (address 003A16)

Timer X mode register (address 2B16)

Timer A mode register (address 1D16)

When not requiring the interrupt occurrence synchronized with

these setting, take the following sequence.

➀ Set the corresponding interrupt enable bit to “0” (disabled).

➁ Set the interrupt edge select bit (active edge switch bit) to “1”.

➂ Set the corresponding interrupt request bit to “0” after 1 or

more instructions have been executed.

➃ Set the corresponding interrupt enable bit to “1” (enabled).

s Timers

• When n (0 to 255) is written to a timer latch, the frequency divi-

sion ratio is 1/(n+1).

• When a count source of timer X, timer Y or timer Z is switched,

stop a count of timer X.

s Timer A

CNTR1 interrupt active edge selection

CNTR1 interrupt active edge depends on the CNTR1 active edge switch bit.

When this bit is “0”, the CNTR1 interrupt request bit is set to “1” at

the falling edge of the CNTR1 pin input signal. When this bit is “1”,

the CNTR1 interrupt request bit is set to “1” at the rising edge of

the CNTR1 pin input signal.

However, in the pulse width HL continuously measurement mode,

CNTR1 interrupt request is generated at both rising and falling

edges of CNTR1 pin input signal regardless of the setting of

CNTR1 active edge switch bit.

s Timer X

CNTR0 interrupt active edge selection

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 re-

quest bit is set to “1” at the rising edge of CNTR0 pin input signal.

s Timer Y: Programmable Generation

Waveform Mode

• Count set value

In the programmable waveform generation mode, values of TYS,

EXPYP, and EXPYS are valid by writing to TYP because the set-

ting to them is executed all at once by writing to TYP. Even when

changing TYP is not required, write the same value again.

• Write timing to TYP

In the programmable waveform generation mode, when the set-

ting value is changed while the waveform is output, set by

software in order not to execute the writing to TYP and the timing

of timer underflow during the secondary interval simultanesously.

• Usage of waveform extension function

The waveform extension function by the timer Y waveform exten-

sion control bit can be used only when “0016” is set to Prescaler Y.

When the value other than “0016” is set to Prescaler Y, be sure to

set “0” to EXPYP and EXPYS.

• Timer Y write mode

When using this mode, be sure to set “1” to the timer Y write con-

trol bit to select “write to latch only”.

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

in any mode.

Also, when Timer Y underflows, the timer Y interrupt request bit is

set to “1”.

Timer Y reloads the value of latch when counting is stopped by the

timer Y count stop bit. (When timer is read out while timer is

stopped, the value of latch is read. The value of timer can be read

out only while timer is operating.)

s Timer Z: Programmable Waveform

Generation Mode

• Count set value

In the programmable waveform generation mode, values of TZS,

EXPZP, and EXPZS are valid by writing to TZP because the set-

ting to them is executed all at once by writing to TZP. Even when

changing TZP is not required, write the same value again.

• Write timing to TZP

In the programmable waveform generation mode, when the set-

ting 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 simultanesously.

• Usage of waveform extension function

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 count source, the waveform extension function cannot be used.

• Timer Z write mode

When using this mode, be sure to set “1” to the timer Z write con-

trol bit to select “write to latch only”.

s Timer Z: Programmable One-shot

Generation Mode

• Count set value

In the programmable one-shot generation mode, the value of

EXPZP becomes valid by writing to TZP. Even when changing

TZP is not required, write the same value again.

• Write timing to TZP

In the programmable 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 un-

derflow simultanesously.

• Usage of waveform extension function

The waveform extension function by the timer Z waveform extension con-

trol 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.

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

waveform extension function cannot be used.

• Timer Z write mode

When using this mode, be sure to set “1” to the timer Z write con-

trol bit to select “write to latch only”.

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