R8C datasheet(90/199 Pages) RENESAS

90 / 199 page

R8C/10 Group

Rev.1.20 Jan 27, 2006

page 80 of 180

REJ09B0019-0120

12.3.3 Programmable One-shot Generation Mode

In this mode, upon program command or external trigger input (input to the INT0 pin), the microcom-

puter outputs the one-shot pulse from the TZOUT pin (see “Table 12.11 Programmable One-shot

Generation Mode Specifications”). When a trigger occurs, the timer starts operating from the point

only once for a given period equal to the set value in the TZPR register. The TZSC is unused in this

mode. Figure 12.24 shows the TYZMR register and PUM register in this mode. Figure 12.25 shows

an operation example in this mode.

Item

Specification

Count source

f1, f2, f8, Timer Y underflow

Count operation

• Downcounts set value in TZPR register

• When the timer underflows, it reloads the contents of reload register before completing

counting and the TZOS bit is “0”.

• When a count stops, the timer reloads the contents of the reload register before it stops.

One-shot pulse output

(n+1)(m+1)/fi

duration

fi : count source frequency, n: set value in PREZ register, m: set value in TZPR register

Count start condition

• Set TZOS bit in TYZOC register to “1” (start one-shot)(1)

• Input active trigger to INT0 pin(2)

Count stop condition

• When reloading is completed after count value was set to "0016"

• When TZS bit in TYZMR register is set to “0” (stop counting)

• When TZOS bit in TYZOC register is set to “0” (stop one-shot)

Interrupt request generation timing In half cycles of count source, after the timer underflows (at the same time as the TZout

output ends) [Timer Z interrupt]

TZOUT pin function

Pulse output

Use timer mode when using this pin as a programmable I/O port.

_______

INT0 pin function

_______

Programmable I/O port, INT0 interrupt input or external trigger input

_______

• When the INOSTG bit in the PUM register is set to “0” (INT0 one-shot trigger disabled)

_______

Programmable I/O port or INT0 interrupt input

_______

• When the INOSTG bit in the PUM register is set to “1” (INT0 one-shot trigger enabled)

_______

external trigger (INT0 interrupt input)

Read from timer

Count value can be read out by reading TZPR register.

Same applies to PREZ register.

Write to timer

Value written to TZPR register is written to reload register only(3).

Same applies to PREZ register.

Select function

• Output level latch select function

Output level for one-shot pulse waveform is selected by TZOPL bit.

_______

• INT0 pin one-shot trigger control function and polarity select function

_______

Trigger input from INT0 pin can be set to active or inactive by INOSTG bit. Also, an

active trigger's polarity can be selected by INOSEG bit.

NOTES:

1. The TZS bit in the TYZMR register must be set to "1" (start counting).

2. The TZS bit must be set to "1" (start counting), the INT0EN bit in the INTEN register to "1" (enabling INT0 input), and

the INOSTG bit in the PUM register to "1" (enabling INT0 one-shot trigger).

_______

Although the trigger input during counting cannot be acknowledged, the INT0 interrupt request is generated.

3. The set values are reflected beginning with the next one-shot pulse after writing to the TZPR register.

Table 12.11 Programmable One-shot Generation Mode Specifications

12.3 Timer (Timer Z)

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