R8C/1A Group, R8C/1B Group
14. Timers
Rev.1.30
Dec 08, 2006
Page 137 of 315
REJ09B0252-0130
NOTES:
1. The TZS bit in the TZMR 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). A trigger
which is input during the count cannot be acknowledged, however an INT0 interrupt request is
generated.
3. The set values are reflected at the following one-shot pulse after writing to the TZPR register.
Table 14.10
Programmable Wait One-Shot Generation Mode Specifications
Item
Specification
Count sources
f1, f2, f8, Timer X underflow
Count operations
• Decrement the value set in Timer Z primary
• When the count of TZPR register underflows, the timer reloads the
contents of the TZSC register before the count is continued.
• When the count of the TZSC register underflows, the timer reloads the
contents of the TZPR register before the count completes and the TZOS
bit is set to 0.
• 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 PREZ register, m: value set in TZPR register
One-shot pulse output time
(n+1)(p+1)/fi
fi: Count source frequency
n: Value set in PREZ register, p: value set in TZSC register
Count start conditions
• Set the TZOS bit in the TZOC register to 1 (one-shot starts).
(1)
• Input active trigger to the INT0 pin
(2)
Count stop conditions
• When reloading completes after timer Z underflows during secondary
period.
• 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 a cycle of the count source after timer Z underflows during
secondary period (complete at the same time as waveform output from the
TZOUT pin) [timer Z interrupt].
TZOUT pin function
Pulse output
(To use this pin as a programmable I/O port, select 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 registers TZPR and PREZ.
Write to timer
The value written to registers TZPR and PREZ is written to the reload
register only
(3)
.
Select functions
• Output level latch select function
The output level of the one-shot pulse waveform is selected by the
TZOPL bit.
• INT0 pin one-shot trigger control function and polarity select function
Trigger input from the INT0 pin can be set to active or inactive by the
INOSTG bit. Also, the active trigger's polarity can be selected by the
INOSEG bit.
