HT46R64/HT46C64
Once an interrupt subroutine is serviced, other inter-
rupts are all blocked (by clearing the EMI bit). This
scheme may prevent any further interrupt nesting. Other
interrupt requests may take place during this interval,
but only the interrupt request flag will be recorded. If a
certain interrupt requires servicing within the service
routine, the EMI bit and the corresponding bit of the
INTC0 or of INTC1 may be set in order to allow interrupt
nesting. Once the stack is full, the interrupt request will
not be acknowledged, even if the related interrupt is en-
abled, until the SP is decremented. If immediate service
is desired, the stack should be prevented from becom-
ing full.
call to location 04H or 08H occurs. The interrupt request
flag (EIF0 or EIF1) and EMI bits are all cleared to disable
other maskable interrupts.
The internal Timer/Event Counter 0 interrupt is initial-
ized by setting the Timer/Event Counter 0 interrupt re-
quest flag (T0F; bit 6 of INTC0), which is normally
caused by a timer overflow. After the interrupt is en-
abled, and the stack is not full, and the T0F bit is set, a
subroutine call to location 0CH occurs. The related inter-
rupt request flag (T0F) is reset, and the EMI bit is
cleared to disable other maskable interrupts.
Timer/Event Counter 1 is operated in the same manner
but its related interrupt request flag is T1F (bit 4 of
INTC1) and its subroutine call location is 10H.
All these interrupts can support a wake-up function. As
an interrupt is serviced, a control transfer occurs by
pushing the contents of the program counter onto the
stack followed by a branch to a subroutine at the speci-
fied location in the ROM. Only the contents of the pro-
gram counter is pushed onto the stack. If the contents of
the register or of the status register (STATUS) is altered
by the interrupt service program which corrupts the de-
sired control sequence, the contents should be saved in
advance.
The time base interrupt is initialized by setting the time
base interrupt request flag (TBF; bit 5 of INTC1), that is
caused by a regular time base signal. After the interrupt
is enabled, and the stack is not full, and the TBF bit is
set, a subroutine call to location 14H occurs. The related
interrupt request flag (TBF) is reset and the EMI bit is
cleared to disable further maskable interrupts.
The real time clock interrupt is initialized by setting the
real time clock interrupt request flag (RTF; bit 6 of
INTC1), that is caused by a regular real time clock sig-
nal. After the interrupt is enabled, and the stack is not
full, and the RTF bit is set, a subroutine call to location
18H occurs. The related interrupt request flag (RTF) is
reset and the EMI bit is cleared to disable further
maskable interrupts.
External interrupts are triggered by a an edge transition
of INT0 or INT1 (ROM code option: high to low, low to
high, low to high or high to low), and the related interrupt
request flag (EIF0; bit 4 of INTC0, EIF1; bit 5 of INTC0)
is set as well. After the interrupt is enabled, the stack is
not full, and the external interrupt is active, a subroutine
Bit No.
Label
EMI
Function
0
1
2
3
4
5
6
Control the master (global) interrupt (1=enabled; 0=disabled)
EEI0
EEI1
ET0I
EIF0
EIF1
T0F
Control the external interrupt 0 (1=enabled; 0=disabled)
Control the external interrupt 1 (1=enabled; 0=disabled)
Control the Timer/Event Counter 0 interrupt (1=enabled; 0=disabled)
External interrupt 0 request flag (1=active; 0=inactive)
External interrupt 1 request flag (1=active; 0=inactive)
Internal Timer/Event Counter 0 request flag (1=active; 0=inactive)
For test mode used only.
7
¾
Must be written as ²0²; otherwise may result in unpredictable operation.
INTC0 (0BH) Register
Bit No.
Label
ET1I
ETBI
ERTI
¾
Function
Control the Timer/Event Counter 1 interrupt (1=enabled; 0=disabled)
Control the time base interrupt (1=enabled; 0:disabled)
Control the real time clock interrupt (1=enabled; 0:disabled)
Unused bit, read as ²0²
0
1
2
3, 7
4
T1F
Internal Timer/Event Counter 1 request flag (1=active; 0=inactive)
Time base request flag (1=active; 0=inactive)
5
TBF
RTF
6
Real time clock request flag (1=active; 0=inactive)
INTC1 (1EH) Register
Rev. 1.80
11
February 14, 2006
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
