R8C16 Datasheet, PDF (110/279 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / R8C/Tiny SERIES

R8C/16 Group, R8C/17 Group
13. Timers
Underflow Signal of
Prescaler X
Set to “1” by program
TXS Bit in TXMR _{“1”}
Register
“0”
“1”
CNTR0i Pin Input _{“0”}
Contents of Timer X
Contents of
Read-Out Buffer1
TXEDG Bit in
TXMR Register ^{“1”}
“0”
TXUND Bit in
TXMR Register ^{“1”}
“0”
Starts
counting
Timer X
reloads
Timer X
reloads
0Fh 0Eh 0Fh 0Eh 0Dh 0Ch 0Bh 0Ah 09h 08h 0Fh 0Eh 0Dh
0Fh
(7)
Retained
0Eh
Retained⁽⁷⁾
0Ah 09h
08h
0Dh
Timer X
reloads
01h 00h 0Fh 0Eh
01h 00h 0Fh 0Eh
Timer X read⁽³⁾
Timer X read⁽³⁾
(2)
(2)
Set to “0” by program⁽⁴⁾
(6)
Set to “0” by program⁽⁵⁾
IR Bit in
TXIC Register
“1”
“0”
IR Bit in INT1IC “1”
Register
“0”
Set to “0” when interrupt request is acknowledged, or set by program
Set to “0” when interrupt request is acknowledged, or set by program
Conditions: A period from one rising edge to the next rising edge of measurement pulse is measured (R0EDG=0)
with the default value of the TX register as 0Fh.
i=0 to 1
NOTES :
1. The contents of the read-out buffer can be read when the TX register is read in pulse period measurement mode.
2. After an active edge of measurement pulse is input, the TXEDG bit in the TXMR register is set to “1” (active edge found)
when the prescale X underflows for the second time.
3. The TX register should be read before the next active edge is input after the TXEDG bit is set to “1” (active edge found).
The contents in the read-out buffer is retained until the TX register is read. If the TX register is not read before the next
active edge is input, the measured result of the previous period is retained.
4. When set to “0” by program, use a MOV instruction to write “0” to the TXEDG in the TXMR register. At the same time,
write “1” to the TXUND bit.
5. When set to “0” by program, use a MOV instruction to write “0” to the TXUND in the TXMR register. At the same time,
write “1” to the TXEDG bit.
6. The TXUND and TXEDG bits are both set to “1” if the timer underflows and reloads on an active edge simultaneously.
In this case, the validity of the TXUND bit should be determined by the contents of the read-out buffer.
7. If the CNTR0 active edge is input, when the prescaler X underflow signal is “H” level, its count value is the one of the
read buffer. If “L” level, the following count value is the one of the read buffer.
Figure 13.10 Operating Example in Pulse Period Measurement Mode
Rev.2.10 Jan 19, 2006 Page 97 of 254
REJ09B0169-0210