Renesas R8C/15 Información técnica Pagina 106

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R8C/14 Group, R8C/15 Group 13. Timers
Rev.2.10 Jan 19, 2006 Page 92 of 253
REJ09B0164-0210
13.1.4 Pulse Width Measurement Mode
Pulse width measurement mode is mode to measure the pulse width of an external signal which
inputs from the INT1
/CNTR0 pin (See Table 13.5 Specification of Pulse Width Measurement
Mode). Figure 13.7 shows the TXMR Register in Pulse Width Measurement Mode. Figure 13.8
shows an Operating Example in Pulse Width Measurement Mode.
Table 13.5 Specification of Pulse Width Measurement Mode
Item Specification
Count Source f1, f2, f8, fRING
Count Operation Decrement
• Continuously counts the selected signal only when the measurement pulse is
“H” level, or conversely only “L” level.
When the timer underflows, the contents in the reload register is reloaded
and the count is inherited
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]
Rising or falling of the CNTR0 input (end of measurement period) [INT1
interrupt]
INT10
/CNTR00,
INT11
/CNTR01 Pin
Function
Measurement pulse input
(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.
Select Function
•INT1
/CNTR0 signal polarity switch function
The R0EDG bit can select during “H” or “L” level as the input pulse
measurement
Measurement pulse input pin select function
The CNTRSEL bit in the UCON register can select the CNTR00 or CNTR01
pin
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