Timer Mode - Renesas M16C FAMILY Hardware Manual

Under development
Preliminary specification
Specifications in this manual are tentative and subject to change.
R8C/11 Group

12.1.1 Timer Mode

In this mode, the timer counts an internally generated count source (See "Table 12.2 Timer Mode
Specifications"). Figure 12.4 shows the TXMR register in timer mode.
Table 12.2 Timer Mode Specifications
Item
Count source
Count operation
Divide ratio
Count start condition
Count stop condition
Interrupt request generation timing When Timer X underflows [Timer X interruption]
INT1/CNTR pin function
0
CNTR pin function
0
Read from timer
Write to timer
Timer X mode register
b7 b6 b5 b4 b3 b2 b1 b0
0 0 0 0
Notes:
1. The IR bit in the INT1IC register may be set to "1" (interrupt requested) when the R0EDG bit is rewritten.
Refer to the paragraph 19.2.5 "Changing Interrupt Source" in the Usage Notes Reference Book.
2. This bit is used to select the polarity of INT1 interrupt in timer mode.
Figure 12.4 TXMR Register in Timer Mode
Rev.0.91 2003 Sep 08
f , f , f , f
1 2 8 32
• Down-count
• When the timer underflows, it reloads the reload register contents before continuing
counting
1/(n+1)(m+1) n: set value of PREX register, m: set value of TX register
Write "1" (count start) to TXS bit in TXMR register
Write "0" (count stop) to TXS bit in TXMR register
Programmable I/O port, or INT1 interrupt input
Programmable I/O port
Count value can be read by reading TX register
Same applies to PREX register.
Value written to TX register is written to both reload register and counter.
Same applies to PREX register.
Symbol
TXMR
0 0
Bit symbol
Bit name
Operation mode
TXMOD0
select bit 0, 1
TXMOD1
INT1/CNTR
R0EDG
switching bit
Timer X count
TXS
start flag
TXOCNT Must set to "0" in timer mode
Operation mode
TXMOD2
select bit 2
TXEDG Must set to "0" in timer mode
Must set to "0" in timer mode
TXUND
page 73 of 184
Specification
Address After reset
008B 00
16 16
Function
b1 b0
0 0 : Timer mode or pulse period
measurement mode
polarity
0
0 : Rising edge
1, 2
1 : Falling edge
0 : Stops counting
1 : Starts counting
0 : Other than pulse period measurement mode
12.1 Timer (Timer X)
RW
RW
RW
RW
RW
RW
RW
RW
RW