R8C/13 Group
12.4 Timer (Timer C)
12.4.1 Input Capture Mode
This mode uses an edge input to TCIN pin or the fRING128 clock as trigger to latch the timer value and
generates an interrupt request. The TCIN input has a digital filter and this prevents an error caused by
noise or so on from occurring. Table 12.13 shows specifications in input capture mode. Figure 12.33
shows an operation example of input capture mode.
Table 12.13 Input Capture Mode Specifications
Item
Count source
Count operation
Specification
f1, f8, f32, fRING-fast
• Count up
• Transfer value in TC register to TM0 register at active edge of measurement pulse
• Value in TC register is set to “000016” when a counting stops
TCC00 bit in TCC0 register is set to “1” (count start)
Count start condition
Count stop condition
TCC00 bit in TCC0 register is set to “0” (count stop)
_____
I
nterrupt request
• When active edge of measurement pulse is input [INT3 interrupt](2)
generation timing
• When Timer C overflows [Timer C interrupt]
______
_______
INT3/TCIN pin function
P10 to P12, P33 to P35
pin function
Programmable I/O port or measurement pulse input (INT3 interrupt input)
Programmable I/O port
Counter value reset timing When TCC00 bit in TCC0 register is set to “0” (capture disabled)
Read from timer(1)
• Count value can be read out by reading TC register.
• Count value at measurement pulse active edge input can be read out by reading TM0
register.
Write to timer
Write to TC register and TM0 register is disabled
_____
Select function
• INT3/TCIN polarity select function
Measurement pulse active edge is selected by TCC03 to TCC04 bits
• Digital filter function
Digital filter sampling frequency is selected by TCC11 to TCC10 bits
• Trigger select function
TCIN input or fRING128 is selected by TCC07 bit.
NOTES:
1. TC register and TM0 register must be read in 16-bit units.
_______
2. The INT3 interrupt is acknowledged by digital filter delay and one count source cycle delay (max.)
Rev.1.20 Jan 27, 2006 page 105 of 205
REJ09B0111-0120
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