R8CSLASH2G datasheet(195/344 Pages) RENESAS

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R8C/2G Group

17. Timers

Rev.1.00

Apr 04, 2008

Page 175 of 318

REJ09B0387-0100

17.2.4

Programmable Wait One-Shot Generation Mode

In programmable wait one-shot generation mode, a one-shot pulse is output from the TRBO pin by a program

or an external trigger input (input to the INT0 pin) (refer to Table 17.10 Programmable Wait One-Shot

Generation Mode Specifications). When a trigger is generated from that point, the timer outputs a pulse only

once for a given length of time equal to the setting value in the TRBSC register after waiting for a given length

of time equal to the setting value in the TRBPR register.

Figure 17.22 shows TRBIOC Register in Programmable Wait One-Shot Generation Mode. Figure 17.23 shows

an Operating Example of Programmable Wait One-Shot Generation Mode.

NOTES:

1. The set value is reflected at the following one-shot pulse after writing to registers TRBSC and TRBPR.

2. Do not set both the TRBPRE and TRBPR registers to 00h.

Table 17.10

Programmable Wait One-Shot Generation Mode Specifications

Item

Specification

Count sources

f1, f2, f8, timer RA underflow

Count operations

• Decrement the timer RB primary setting value.

• When a count of the timer RB primary underflows, the timer reloads the contents of

timer RB secondary before the count continues.

• When a count of the timer RB secondary underflows, the timer reloads the contents

of timer RB primary before the count completes and the TOSSTF bit is set to 0

(one-shot stops).

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

stops.

Wait time

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

fi: Count source frequency

n: Value set in the TRBPRE register, m Value set in the TRBPR register(2)

One-shot pulse output time

(n+1)(p+1)/fi

fi: Count source frequency

n: Value set in the TRBPRE register, p: Value set in the TRBSC register

Count start conditions

• The TSTART bit in the TRBCR register is set to 1 (count starts) and the next trigger

is generated.

• Set the TOSST bit in the TRBOCR register to 1 (one-shot starts).

• Input trigger to the INT0 pin

Count stop conditions

• When reloading completes after timer RB underflows during secondary period.

• When the TOSSP bit in the TRBOCR register is set to 1 (one-shot stops).

• When the TSTART bit in the TRBCR register is set to 0 (starts counting).

• When the TSTOP bit in the TRBCR register is set to 1 (forcibly stops counting).

Interrupt request generation

timing

In half a cycle of the count source after timer RB underflows during secondary period

(complete at the same time as waveform output from the TRBO pin) [timer RB

interrupt].

TRBO pin function

Pulse output

INT0 pin functions

• When the INOSTG bit in the TRBIOC register is set to 0 (INT0 one-shot trigger

disabled): programmable I/O port or INT0 interrupt input

• When the INOSTG bit in the TRBIOC 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 registers TRBPR and TRBPRE.

Write to timer

• When registers TRBPRE, TRBSC, and TRBPR are written while the count stops,

values are written to both the reload register and counter.

• When registers TRBPRE, TRBSC, and TRBPR are written to during count

operation, values are written to the reload registers only.(1)

Select functions

• Output level select function

The TOPL bit in the TRBIOC register selects the output level of the one-shot pulse

waveform.

• One-shot trigger select function

Refer to 17.2.3.1 One-Shot Trigger Selection.

• TRBO pin select function

P3_1 or P1_3 is selected by the TRBOSEL bit in the PINSR2 register.

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