
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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