Hitachi AP1 Data Book page 319

4-bit single-chip microcomputer
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-----------------------------------------------------------------------HMCS404AC
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-8 (TCBL: $OOA, TC8U: $OOB)
TLRL: $OOA, TLRU: $008
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 $00 by
the MCU reset.
The counter value of TIMER-B can be obtained by reading
PMR:$ 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 (IFTA: $001,2)
The TIMER-A Interrupt Request Flag is set by the overflow
output of TIMER-A.
• TIMER-A Interrupt Mask (IMTA: $001,3)
TIMER-A Interrupt Mask prevents an interrupt request
generated by TIMER-A Interrupt Request Flag.
Table 13. TIMER-A Interrupt Request Flag
TIMER-A Interrupt
Request Flag
o
I nterrupt Request
No
Yes
Table 14. TIMER-A Interrupt Mask
TIMER-A Interrupt
Mask
o
Interrupt Request
Enable
Disable (Mask)
• TIMER·B Interrupt Request Flag (IFTB: $002,0)
The TIMER-B Interrupt Request Flag is set by the overflow
output of TIMER-B_
• TIMER-B Interrupt Mask (IMTB: $002, 1)
TIMER-B Interrupt Mask prevents an interrupt request
generated by TIMER-B Interrupt Request Flag_
SMR:$005
Transfer clock selection
R 40 /SCK pin mode selection
L . -_ _ _ _ _
R42/S0 pin mode selection
' - - - - - - - - - R 41 /SI pin mode selection
' - - - - - - - - - - - - R3211NTo pin mode selection
' - - - - - - - - - - - - - - R33/INTI pin mode selection
TMA:$ 008
TMB:$009
I)<ITMA21TMA 11TMAOI
, . ' l'
L
TIMER-B input clock selection
r
l
Auto-reload function selection
~
TlMER-A input clock selection
Fig. 14 Mode Register Configuration and Function
317

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