
R8C/3GM Group
16. General Overview of Timers
R01UH0284EJ0100 Rev.1.00
Aug 09, 2011
16. General Overview of Timers
The MCU has two 8-bit timers with 8-bit prescalers, a 16-bit timer, and a timer with a 4-bit counter and an 8-bit
counter. The two 8-bit timers with 8-bit prescalers are timer RA and timer RB. These timers contain a reload register to
store the default value of the counter. The 16-bit timer is timer RC, and has input capture and output compare
functions. The 4-bit and 8-bit counters are timer RE, and has an output compare function. All the timers operate
independently.
Note:
1.
Rectangular waves are output in these modes. Since the waves are inverted at each overflow, the “H” and “L” level widths of
the pulses are the same.
Table 16.1
Functional Comparison of Timers
Item
Timer RA
Timer RB
Timer RC
Timer RE
Configuration
8-bit timer with 8-bit
prescaler
(with reload register)
8-bit timer with 8-bit
prescaler
(with reload register)
16-bit timer
(with input capture and
output compare)
4-bit counter
8-bit counter
Count
Decrement
Increment
Count sources
f1
f2
f8
fOCO
fC32
fC
f1
f2
f8
Timer RA underflow
f1
f2
f4
f8
f32
fOCO40M
fOCO-F
TRCCLK
f4
f8
f32
fC4
Function Count of the
internal count
source
Timer mode
(output compare
function)
—
Count of the
external count
source
Event counter mode
—
Timer mode
(output compare
function)
—
External pulse
width/period
measurement
Pulse width
measurement mode,
pulse period
measurement mode
—
Timer mode
(input capture function;
4 pins)
—
PWM output
Programmable
waveform generation
mode
Timer mode
(output compare
PWM mode (3 pins),
PWM2 mode (1 pin)
—
One-shot
waveform
output
—
Programmable one-shot
generation mode,
Programmable wait
one-shot generation
mode
PWM mode (3 pins)
—
Three-phase
waveforms
output
——
Timer
Timer mode
(only fC32 count)
—
Real-time clock mode
Input pin
TRAIO
INT0
INT0, TRCCLK,
TRCTRG, TRCIOA,
TRCIOB, TRCIOC,
TRCIOD
—
Output pin
TRAO, TRAIO
TRBO
TRCIOA, TRCIOB,
TRCIOC, TRCIOD
—
Related interrupt
Timer RA interrupt
Timer RB interrupt,
INT0 interrupt
Compare match/input
capture A to D interrupt,
Overflow interrupt,
INT0 interrupt
Timer RE interrupt
Timer stop
Provided