HT46R47
Timer/Event Counter
measure time intervals or pulse widths, or to
generate an accurate time base.
A timer/event counter (TMR) is implemented in
the microcontroller. The timer/event counter
contains an 8-bit programmable count-up coun-
ter and the clock may come from an external
source or the system clock.
There are 2 registers related to the timer/event
counter; TMR ([0DH]), TMRC ([0EH]). Two phys-
ical registers are mapped to TMR location; writ-
ing TMR makes the starting value be placed in
the timer/event counter preload register and
reading TMR gets the contents of the timer/event
counter. The TMRC is a timer/event counter con-
trol register, which defines some options.
Using the internal system clock, there is only
one reference time-base. The internal clock
source comes from fSYS. The external clock in-
put allows the user to count external events,
Label (TMRC)
Bits
Function
To define the prescaler stages, PSC2, PSC1, PSC0=
000: fINT=fSYS
001: fINT=fSYS/2
010: fINT=fSYS/4
011: fINT=fSYS/8
100: fINT=fSYS/16
101: fINT=fSYS/32
110: fINT=fSYS/64
111: fINT=fSYS/128
PSC0~PSC2
0~2
To define the TMR active edge of timer/event counter
(0=active on low to high; 1=active on high to low)
TE
3
To enable/disable timer counting
(0=disabled; 1=enabled)
TON
4
5
¾
Unused bit, read as ²0²
To define the operating mode
01=Event count mode (external clock)
10=Timer mode (internal clock)
11=Pulse width measurement mode
00=Unused
TM0
TM1
6
7
TMRC register
P
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6
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Timer/Event Counter
16
Rev. 1.40
July 18, 2001
ETC [ ETC ]
