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7540 Group User’s Manual
2-98
APPLICATION
2.5 Timer Y and timer Z
Fig. 2.5.40 Example of control procedure
0
1
Wait one-shot generation routine
1
0
1
0
11
INT0 rising edge active
1
Timer Z interrupt processing routine
RTI
0
RTS
Timer Z primary (Address 2716)
Prescaler Z (Address 2516)
Set pull-up control register
Set port P1P3 control register
TYZM(Address 2016)
Timer Z count start (Note 7)
Set the standby state to accept
one-shot start trigger
INTEDGE(Address 3A16)
Set interrupt edge selection register
Change of timer Z
Timer Z primary waveform
generation not extended (Note 2)
Timer Z secondary waveform
generation not extended (Note 2)
Initial state: TZP: “H” interval,
TZS: “L” interval after underflow
Stop at “H” after underflow
INT0 pin one-shot trigger valid (Note 3)
INT0 pin rising edge trigger (Note 3)
PUM(Address 2416)
TCSS(Address 2E16)
Timer Z count source selected
Set port P02 to the output mode.
Set “0” to the timer Z interrupt enable bit.
(Timer Z interrupt disabled)
Set value to timer Z (Notes 2, 4, 5, 6)
Set timer count source set register (Note 3)
TYZM(Address 2016)
Set timer Y, Z mode register
Programmable wait one-shot
generation mode
Writing to only latch (Note 2)
Timer Z count stop
Set “1” to the timer Z interrupt enable bit.
(Timer Z interrupt enabled)
Set “0” to the imer Z interrupt request bit.
Set timer Y, Z waveform output control register
Set port P37 to the input mode.
Notes 1: When using this mode, be sure to select “write to latch only”.
2: 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 and EXPZS. Also, when the timer Y
underflow is selected as the timer Z count source, the
waveform extension function cannot be used.
3: Stop timer Z to change the INT0 pin one-shot trigger control
bit and INT0 one-shot trigger active edge selection bit.
4: 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.
5: 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 Z underflow simultanesously.
6: Count values of the primary interval (during wait) and
secondary interval (during one-shot output) can be checked
by reading TZP (TZS is undefined at read).
7: In this state, timer count is not started.
Timer Z secondary (Address 2616)