Datasheet

Section 13 Timer RA
REJ09B0465-0300 Rev. 3.00 Page 401 of 982
Sep 17, 2010
H8S/20103, H8S/20203, H8S/20223, H8S/20115, H8S/20215, H8S/20235 Group
Section 13 Timer RA
The timer RA is an 8-bit reload timer with a prescaler. The prescaler and the timer are comprised
of a reload register and a counter, respectively.
13.1 Overview
• Operating mode: 5 modes
Timer mode: Counts internal count sources.
Pulse output mode: Counts internal count sources and produces a toggle output in timer
underflow.
Event counter mode: Counts external events.
Pulse width measurement mode: Measures the pulse width of external pulses.
Pulse cycle measurement mode: Measures the pulse cycle of external pulses.
• Selection of eight count sources
φ, φ/2, φ/8, φ/32, φ/64, φ/128, φsub, or an external event input to the TRAIO pin.
• An interrupt generated on an underflow of the counter
Data bus
Reload
register
Reload
register
Counter
Counter
Underflow signal
Timer RA
interrupt
Measurement-complete signal
Toggle flipflop
Count control
circuit
Polarity
switching
Digital
filter
Event count mode
TRATRTRAPRE
Write to TRAMR register
Write 1 to TSTOP bit
TEDGSEL
TOPCR
TOENA
TRAO pin
TRAIO pin
CLR
CK
Q
Q
Pulse output mode
Pulse width measurement mode
Pulse cycle measurement mode
Timer mode
Pulse output mode
TCKCUT
TSTART
TCK[2:0]
φ
φ/8
φ/2
φsub
φ/32
φ/64
φ/128
TIPF[1:0]
Pulse width measurement mode
Pulse cycle measurement mode
Figure 13.1 Block Diagram of Timer RA