R8C/20 Group, R8C/21 Group 14. Timers
Rev.2.00 Aug 27, 2008 Page 152 of 458
REJ09B0250-0200
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 14.10 Programmable Wait One-Shot Generation Mode Specifications
Item Specification
Count Sources f1, f2, f8, timer RA underflow
Count Operations • Decrement the setting value in timer RB primary
• When a count of timer RB primary underflows, the timer reloads the
contents of the timer RB secondary before the count continues.
• When a count of timer RB secondary underflows, the timer reloads the
contents of the timer RB primary before the count completes and the
TOSSTF bit is set to 0 (one-shot stops).
• When a 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: Setting value in the TRBPRE register, m: Setting value in the TRBPR register
(2)
One-Shot Pulse Output Time (n+1)(p+1)/fi
fi: Count source frequency
n: Setting value in the TRBPRE register, p: Setting value 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 0 (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 cycles 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 the TRBPR and TRBPRE
registers.
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 TRBIO register can select the output level of the
one-shot pulse waveform.
• One-shot trigger select function
Refer to 14.2.3.1 One-Shot Trigger Selection.
To Next Page
Loading...
Need help?
General
