
R8C/14 Group, R8C/15 Group 13. Timers
Rev.2.10 Jan 19, 2006 Page 87 of 253
REJ09B0164-0210
13.1.1 Timer Mode
Timer mode is mode to count the count source which is internally generated (See Table 13.2
Specification of Timer Mode). Figure 13.4 shows the TXMR Register in Timer Mode.
Figure 13.4 TXMR Register in Timer Mode
Table 13.2 Specification of Timer Mode
Item Specification
Count Source f1, f2, f8, fRING
Count Operation • Decrement
• When the timer underflows, the contents in the reload register is reloaded and
the count is inherited
Divide Ratio 1/(n+1)(m+1) n: setting value of PREX register, m: setting value of TX register
Count Start Condition Write “1” (count starts) to the TXS bit in the TXMR register
Count Stop Condition Write “0” (count stops) to the TXS bit in the TXMR register
Interrupt Request
Generation Timing
When Timer X underflows [Timer X interrupt]
INT10
/CNTR00,
INT11
/CNTR01 Pin
Function
Programmable I/O port, or INT1
interrupt input
CNTR0
Pin Function
Programmable I/O port
Read from Timer The count value can be read by reading the TX and PREX registers
Write to Timer • When writing to the TX and PREX registers while the count stops, the value is
written to both the reload register and counter.
• When writing to the TX and PREX registers during the count, the value is
written to each reload register of the TX and PREX registers at the following
count source input and the data is transferred to the counter at the second
count source input and the count re-starts at the third count source input.
Timer X Mode Register
Symbol Address After Reset
TXMR
008Bh 00h
Bit Symbol Bit Name Function RW
INT1
____
/CNTR0 Signal
Polarity Sw itch Bit
(1, 2)
NOTES :
1.
2.
3. Refer to
20.4.2 Timer X
for precautions on the TXS bit.
The IR bit in the INT1IC register may be set to “1” (requests interrupt) when the R0EDG bit is rew ritten.
Refer to
20.2.5 Changing Interrupt Factor
.
R0EDG RW
RW
TXOCNT RW
TXMOD2
This bit is used to select the polarity of INT1
____
interrupt in timer mode.
Set to “0” in timer mode
TXMOD0 RW
Operating Mode Select Bit 0, 1
b1 b0
0 0 : Timer mode or pulse period measurement
mode
TXMOD1 RW
00
b7 b6 b5 b4
00000
RW
b3 b2
0 : Rising edge
1 : Falling edge
TXS
Timer X Count Start Flag
(3)
0 : Stops counting
1 : Starts counting
b1 b0
RW
TXUND RW
TXEDG Set to “0” in timer mode
Set to “0” in timer mode
Operating Mode Select Bit 2 0 : Other than pulse period measurement mode
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