Hitachi AP1 Data Book page 313

-----------------------------------------------------------------------HMCS404AC
Instruction
Cycles
Instruction
execution
Interrupt
accepted
2
Stacking.
Reset of lIE
3
Stacking,
Vector address
is generated
4 5
..!MPL instruction execution on the
vector address
6
Fig.7 Interrupt Servicing Sequence
Instruction
Execution at
starting address
of the interrupt
routine
• Interrupt Enable Flag (lIE: $000,0)
The Interrupt Enable Flag controls enable/disable of all inter-
rupt requests as shown in Table
3.
The Interrupt Enable Flag is
reset by the interrupt servicing and set by RTNI instruction.
Table 3. Interrupt Enable Flag
Interrupt Enable Flag
Interrupt Enable/Disable
o
Disable
Enable
• External Interrupt
(I
NT
0,
I NT
I )
To use external interrupt, select R32 /INT
0,
R33 /INT I port
for INTo, INTI mode by setting the Port Mode Register (PMR:
$004).
The External Interrupt Request Flags (IFO, IF!) are set at
the falling edge of INT
0,
INT I inputs.
INT
1
input can be used as a clock signal input of TIMER-B.
Then, TIMER-B counts up at each falling edge of input. When
using INTI as TIMER-8 external event, an External Interrupt
Mask (1M!) has to be set so that the interrupt request by INTI
will not be accepted.
• External Interrupt Request Flag
(I
FO: $000,2, I F1: $001,0)
The External Interrupt Request Flags (IFO, 1Ft) are set at
the falling edges of INTo, INT
1
in puts respectively.
• External Interrupt Mask (lMO: $000,3, IM1: $001,1)
The External Interrupt Mask is used to mask the external
interrupt requests.
Table 4. External Interrupt Request Flag
External Interrupt Request Flags
Interrupt Requests
o
No
Yes
311
Table 5. External I nterrupt Mask
External Interrupt Masks Interrupt Requests
o
Enable
Disable (masks)
• Port Mode Register (PMR: $004)
The Port Mode Register is a 4-bit write-only register which
controls the R32 /INT
0
pin, R33 lINT I pin,
~
I lSI pin and
~2
ISO pin as shown in Table 6. The Port Mode Register will
be initialized to $0 by MeV reset, so that all these pins are set
to a port mode.
Table
6.
Port Mode Register
PMR
R33/INTI pin
bit 3
0 Used as R33 port input/output pin
Used as I NT I input pin
PMR
Rn
/1
NT
0
pin
bit 2
0 Used as R32 port input/output pin
Used as I NT
0
input pin
PMR
R 41 /SI pin
bit 1
0 Used as R41 port input/output pin
Used as SI input pin
PMR
bit 0
R42/S0 pin
0
Used as R42 port input/output pin
Used as SO output pin