R8C/10 Group
Rev.1.20 Jan 27, 2006 page 86 of 180
REJ09B0019-0120
12.4 Timer C
Timer C is a 16-bit free-running timer. Figure 12.28 shows a block diagram of Timer C. The Timer C uses
an edge input to TCIN pin or the fRING128 clock as trigger to latch the timer count 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 Timer C specifications. Figure 12.29 shows TC, TM0, TCC0, and
TCC1 registers. Figure 12.30 shows an operation example of Timer C.
Item Specification
Count source f1, f8, f32
Count operation • 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
Count start condition TCC00 bit in TCC0 register is set to “1” (capture enabled)
Count stop condition TCC00 bit in TCC0 register is set to “0” (capture disabled)
I
nterrupt request
_____
• When active edge of measurement pulse is input [INT3 interrupt]
generation timing • When Time C underflows [Timer C interrupt]
______
INT3/TCIN pin function Programmable I/O or measurement pulse input
Counter value reset timing When TCC00 bit in TCC0 register is set to “0” (capture disabled)
Read from timer
(1)
• Counter value can be read out by reading TC register.
• Counter 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 switching 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.
TM0 register
Upper 8 bits
Lower 8 bits
Counter
f
1
f
8
f
32
Edge detection
f
RING128
Timer C interrupt
TCC07=1
Transfer signal
Digital
filter
f
1
f
8
f
32
TCC11 to TCC10
=01
2
TC register
Data bus
Upper 8 bits
Lower 8 bits
INT3/TC
IN
=10
2
=11
2
TCC07=0
TCC02 to TCC01
=00
2
=01
2
=10
2
INT3 interrupt
TCC11 to TCC10
=00
2
Other than 00
2
TCC01, TCC02, TCC07: Bits in TCC0 register
TCC10, TCC11: Bits in TCC1 register
Sampling
clock
Table 12.13 Timer C Specifications
Figure 12.28 Timer C Block Diagram
12.4 Timer (Timer C)
(29 pagine)
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