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R8C/1A Group, R8C/1B Group 14. Timers
Rev.1.30 Dec 08, 2006 Page 147 of 315
REJ09B0252-0130
14.3.1 Input Capture Mode
In input capture mode, the edge of the TCIN pin input signal or the fRING128 clock is used as a trigger to latch
the timer value and generate an interrupt request. The TCIN input contains a digital filter, and this prevents
errors caused by noise or the like from occurring. Table 14.11 shows the Input Capture Mode Specifications.
Figure 14.30 shows an Operating Example in Input Capture Mode.
NOTES:
1. The INT3 interrupt includes a digital filter delay and one count source (max.) delay.
2. Read registers TC and TM0 in 16-bit unit.
Table 14.11 Input Capture Mode Specifications
Item Specification
Count sources f1, f8, f32, fRING-fast
Count operations • Increment
• Transfer the value in the TC register to the TM0 register at the active edge
of the measured pulse.
• The value in the TC register is set to 0000h when the count stops.
Count start condition The TCC00 bit in the TCC0 register is set to 1 (count starts).
Count stop condition The TCC00 bit in the TCC0 register is set to 0 (count stops).
Interrupt request
generation timing
• When the active edge of the measured pulse is input [INT3 interrupt].
(1)
• When timer C overflows [timer C interrupt].
INT3/TCIN pin function Programmable I/O port or the measured pulse input (INT3 interrupt input)
P1_0 to P1_2, P3_3 to
P3_5 pin functions Programmable I/O port
Counter value reset timing When the TCC00 bit in the TCC0 register is set to 0 (count stops).
Read from timer
(2) • The count value can be read out by reading the TC register.
• The count value at the measured pulse active edge input can be read out
by reading the TM0 register.
Write to timer Write to the TC and TM0 registers is disabled.
Select functions
• INT3/TCIN polarity select function
Bits TCC03 to TCC04 can select the active edge of the measured pulse.
• Digital filter function
Bits TCC11 to TCC10 can select the digital filter sampling frequency.
• Trigger select function
The TCC07 bit can select the TCIN input or the fRING128.