Renesas R8C/20 User Manual

R8C/20 Group, R8C/21 Group 14. Timers
Rev.2.00 Aug 27, 2008 Page 120 of 458
REJ09B0250-0200
14.1 Timer RA
Timer RA is an 8-bit timer with an 8-bit prescaler.
The prescaler and timer consist of the reload register and counter. The reload register and counter are allocated at
the same address. When accessing the TRAPRE and TRA registers, the reload register and counter can be accessed
(refer to Table 14.2 to 14.6 the Specification of Each Modes).
The count source for timer RA is the operating clock that regulates the timing of timer operations such as counting
and reloading.
Figure 14.1 shows the Block Diagram of Timer RA. Figures 14.2 to 14.4 show the registers associated with Timer
RA.
Timer RA contains five operation modes listed as follows:
• Timer mode: The timer counts an internal count source.
• Pulse output mode: The timer counts an internal count source and outputs the pulses which
invert the polarity by underflow of the timer.
• Event counter mode: The timer counts external pulses.
• Pulse width measurement mode: The timer measures the pulse width of an external pulse.
• Pulse period measurement mode: The timer measures the pulse period of an external pulse.
Figure 14.1 Block Diagram of Timer RA
TCSTF
bit
TCKCUT
bit
= 000b
= 001b
= 011b
f2
f8
f1
= 010b
fOCO
TCK2 to TCK0 bit
Counter
Reload
register
TRAPRE register
(Prescaler)
Peripheral data bus
Timer RA interrupt
Write to TRAMR register
Write to TSTOP bit 1
TCSTF, TSTOP: TRACR register
TEDGSEL, TOPCR, TOENA, TIOSEL, TIPF1, TIPF0: TRAIOC register
TMOD2 to TMOD0, TCK2 to TCK0, TCKCUT: TRAMR register
Toggle flip-flop
Q
Q
CLR
CK
TOENA bit
TRAO pin
INT1/TRAIO (P1-5) pin
TMOD2 to TMOD0
= 011b or 100b
Polarity
switching
Digital
filter
Counter
Reload
register
TRA register
(Timer)
TIPF1 to TIPF0 bit
= 00b
= 10b
f8
f1
= 11b
f32
TIOSEL = 0
TIOSEL = 1
Count control
circle
TMOD2 to TMOD0 = 001b
TOPCR bit
Underflow signal
Measurement completion signal
TIPF1 to
TIPF0 bit
= Except 00b
= 00b
INT1/TRAIO (P1-7) pin
TEDGSEL = 1
TEDGSEL = 0
TMOD2 to TMOD0
= Except 010b
TMOD2 to TMOD0
= 010b

Renesas R8C/20 Specifications

General

Brand	Renesas
Model	R8C/20
Category	Control Unit
Language	English