HMCS404C----------------------------------------------------------------
Table 12. Timer Mode Register B
TMB
Bit
3
Auto·reload Function
o
No
Yes
TMB
Prescaler
Divide Ratio,
Bit
2
Bit
1
Bit
0
Clock
Input
Source
0 0
0
+2048
0 0
1
512
0
1
0
128
0
1
1
32
1
0
0
8
1
0
1
4
1
1
0
2
1
1
1
INTI
(External Event Input)
•
TIMER-B
(TCBL:
$OOA,
TCBU:
$OOB)
TLRL:
$OOA,
TLRU:
$OOB
TIMER·B consists
of
an 8-bit write-only Timer Load
Regis-
ter, and an 8-bit read-only Timer/Event Counter. Each
of
them
has a low-order digit (TCBL:
$OOA,
TLRL:
$OOA)
and a high-
order digit (TCBU:
$OOB,
TLRU:
$OOB).
The Timer/Event Counter can be initialized by writing data
into the Timer Load Register. In this case, write the low-order
digit first, and then the high-order digit. The Timer/Event
Counter
is
initialized at the time when the high-order digit
is
written. The Timer Load Register will
be
initialized
to
$00 by
the
MCV
reset.
The counter value
of
TIMER-B can be obtained
by
reading
PMR:$
004
the Timer/Event Counter. In this case, read the high-order digit
first, and then the low-order digit. The count value
of
low-order
digit
is
latched at the time when the high·order digit
is
read.
• TIMER-A Interrupt Request
Flag
(lFTA:
$001,2)
The TIMER-A Interrupt Request Flag
is
set by the overflow
output
of
TIMER-A.
• TIMER-A Interrupt
Mask
(lMTA:
$001,3)
TIMER-A Interrupt
Mask
prevents an interrupt request
generated by TlMER-A Interrupt Request Flag.
Table 13.
TIMER·A
Interrupt Request
Flag
TIMER·A
Interrupt
Request Flag
o
Interrupt Request
No
Yes
Table 14.
TlMER·A
Interrupt
Mask
TIMER·A
Interrupt
Mask
o
Interrupt Request
Enable
Disable
(Mask)
•
TIMER-B
Interrupt Request
Flag
(lFTB: $002, 0)
The TIMER-B Interrupt Request Flag
is
set by the overflow
output
of
TIMER-B.
•
TIMER-B
Interrupt
Mask
(lMTB:
$002, 1)
TIMER-B Interrupt Mask prevents an interrupt request
generated by TIMER-B Interrupt Request Flag.
SMR:$
005
Transfer
clock
selection
R.o/SCK
pin
mode selection
'------
R.
a
ISO
pin
mode selection
L-
_______
R.I/SI
pin
mode selection
L-
_________
R3a/
iNT
o
pin
mode selection
L-
____________
Ru/lNTI
pin
mode selection
TMA:$008
TMB:$009
I><ITMA21TMA
,I™AOI
. '
l'
L
TIMER·B
input
clock
selection
r l Auto-reload
function
selection
~
TIMER·A
input
clock
selection
Fig.
14
Mode Register Configuration
and
Function
242
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