R8CSLASH15 datasheet(120/277 Pages) RENESAS

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R8C/14 Group, R8C/15 Group

13. Timers

Rev.2.10

Jan 19, 2006

Page 108 of 253

REJ09B0164-0210

13.2.3

Programmable One-shot Generation Mode

Programmable one-shot generation mode is mode to output the one-shot pulse from the TZOUT pin

by a program or an external trigger input (input to the INT0 pin). (see Table 13.9 Specification of

Programmable One-Shot Generation Mode). When a trigger is generated, the timer starts

operating from the point only once for a given period equal to the set value in the TZPR register. The

TZSC register is unused in this mode. Figure 13.19 shows the TZMR and PUM Registers in

Programmable One-Shot Generation Mode. Figure 13.20 shows an Operating Example in

Programmable One-Shot Generation Mode.

NOTES:

1. Set the TZS bit in the TZMR register to “1” (count starts).

2. Set the TZS bit to “1” (count starts), the INT0EN bit in the INTEN register to “1” (enables INT0 input),

and the INOSTG bit in the PUM register to “1” (INT0 one-shot trigger enabled). A trigger which is

input during the count cannot be acknowledged, however the INT0 interrupt request is generated.

3. The set value is reflected at the following one-shot pulse after writing to the TZPR register.

Table 13.9

Specification of Programmable One-Shot Generation Mode

Item

Specification

Count Source

f1, f2, f8, Timer X underflow

Count Operation

• Decrement the setting value in the TZPR register

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

the count completes and the TZOS bit is set to “0” (one-shot stops).

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

it stops.

One-Shot Pulse

Output Time

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

fi: Count source frequency, n: setting value in PREZ register, m: setting value in

TZPR register

Count Start Condition • Set the TZOS bit in the TZOC register to “1” (one-shot starts) (1)

• Input active trigger to the INT0 pin(2)

Count Stop Condition • When reloading completes after the count value is set to “00h”

• When the TZS bit in the TZMR register is set to “0” (count stops)

• When the TZOS bit in the TZOC register is set to “0” (one-shot stops)

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

(When using this function as a programmable I/O port, set to timer mode.)

INT0 Pin Function

• 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

The count value can be read out by reading the TZPR and PREZ registers.

Write to Timer

The value written to the TZPR and PREZ registers is written to the reload register

only(3).

Select Function

• Output level latch select function

The TZOPL bit can select the output level of the one-shot pulse waveform.

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

The INOSTG bit can select the trigger input from the INT0 pin is active or

inactive. Also, the INOSEG bit can select the active trigger polarity.

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