7540 datasheet(70/366 Pages) RENESAS

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REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

7540 Group

HARDWARE

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 exten-

sion 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. 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 Wait One-shot

Generation Mode

• Count set value

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.

• Write timing to TZP

In the programmable wait one-shot generation mode, when the

setting value is changed while the waveform is output, set by soft-

ware 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 exten-

sion 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”.

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

bit in any mode.

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

set to “1”.

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

timer Z 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 Serial I/O

• Serial I/O interrupt

When setting the transmit enable bit to “1”, the serial I/O transmit

interrupt request bit is automatically set to “1”. When not requiring

the interrupt occurrence synchronized with the transmission en-

abled, take the following sequence.

➀ Set the serial I/O transmit interrupt enable bit to “0” (disabled).

➁ Set the transmit enable bit to “1”.

➂ Set the serial I/O transmit interrupt request bit to “0” after 1 or

more instructions have been executed.

➄ Set the serial I/O transmit interrupt enable bit to “1” (enabled).

• I/O pin function when serial I/O1 is enabled.

The functions of P12 and P13 are switched with the setting values

of a serial I/O1 mode selection bit and a serial I/O1 synchronous

clock selection bit as follows.

(1) Serial I/O1 mode selection bit

→ “1” :

Clock synchronous type serial I/O is selected.

Setup of a serial I/O1 synchronous clock selection bit

“0” : P12 pin turns into an output pin of a synchronous clock.

“1” : P12 pin turns into an input pin of a synchronous clock.

Setup of a SRDY1 output enable bit (SRDY)

“0” : P13 pin can be used as a normal I/O pin.

“1” : P13 pin turns into a SRDY output pin.

(2) Serial I/O1 mode selection bit

→ “0” :

Clock asynchronous (UART) type serial I/O is selected.

Setup of a serial I/O1 synchronous clock selection bit

“0”: P12 pin can be used as a normal I/O pin.

“1”: P12 pin turns into an input pin of an external clock.

When clock asynchronous (UART) type serial I/O is selected, it is

P13 pin. It can be used as a normal I/O pin.

s A/D Converter

• The comparator uses internal capacitors whose charge will be

lost if the clock frequency is too low.

Make sure that f(XIN) is 500kHz or more during A/D conversion.

• As for AD translation accuracy, on the following operating condi-

tions, accuracy may become low.

(1) Since the analog circuit inside a microcomputer becomes sensi-

tive to noise when VREF voltage is set up lower than Vcc

voltage, accuracy may become low rather than the case where

VREF voltage and Vcc voltage are set up to the same value.

(2) When VREF voltage is lower than [3.0 V], the accuracy at the

low temperature may become extremely low compared with

that at room temperature When the system would be used at

low temperature, the use at VREF=3.0 V or more is recom-

mended.

NOTES ON PERIPHERAL FUNCTIONS

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