Timer X - Renesas R8C/18 Series Hardware Manual

R8C/18 Group, R8C/19 Group
14.1

Timer X

Timer X is an 8-bit timer with an 8-bit prescaler.
The prescaler and timer each consist of a reload register and counter. The reload register and counter
are allocated at the same address, and can be accessed when accessing registers PREX and TX (refer
to Tables 14.2 to 14.6 the Specifications of Each Modes).
Figure 14.1 shows a Block Diagram of Timer X. Figures 14.2 and 14.3 show the registers associated
with Timer X.
Timer X has the following five operating modes:
• Timer mode:
•
Pulse output mode:
•
Event counter mode:
• Pulse width measurement mode:
•
Pulse period measurement mode: The timer measures the pulse period of an external pulse.
TXCK1 to TXCK0
fRING
CNTRSEL = 1
INT11/CNTR01
INT10/CNTR00
CNTRSEL = 0
CNTR0
Figure 14.1 Block Diagram of Timer X
Rev.1.30 Apr 14, 2006
REJ09B0222-0130
The timer counts the internal count source.
The timer counts the internal count source and outputs pulses
which invert the polarity by underflow of the timer.
The timer counts external pulses.
The timer measures the pulse width of an external pulse.
TXMOD1 to TXMOD0
= 00b
f1
= 00b or 01b
= 01b
f8
= 10b
= 11b
= 11b
f2
= 10b
Polarity
switching
TXMOD1 to TXMOD0
R0EDG = 1
bits = 01b
TXOCNT bit
R0EDG = 0
Page 103 of 233
Data bus
Reload register
Counter
PREX register
TXS bit
Q
Toggle flip-flop
CK
Q
CLR
TXMOD0 to TXMOD1, R0EDG, TXS, TXOCNT: Bits in TXMR register
TXCK0 to TXCK1: Bits in TCSS register
CNTRSEL: Bit in UCON register
Reload register
Counter Timer X interrupt
TX register
INT1 interrupt
Write to TX register
Bits TXMOD1 to TXMOD0 = 01b
14. Timers