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TMP86FS64FG
3.3 Interrupt Source Selector (INTSEL)
Each interrupt source that shares the interrupt source level with another interrupt source is allowed to enable the
interrupt latch only when it is selected in the INTSEL register. The interrupt controller does not hold interrupt
requests corresponding to interrupt sources that are not selected in the INTSEL register. Therefore, the INTSEL reg-
ister must be set appropriately before interrupt requests are generated.
The following interrupt sources share their interrupt source level; the source is selected onnthe register INTSEL.
1. INTTBT and INT2 share the interrupt source level whose priority is 9.
2. INTTC1 and INT3 share the interrupt source level whose priority is 10.
3. INTSIO1 and INT4 share the interrupt source level whose priority is 14.
4. INTTRX and INT5 share the interrupt source level whose priority is 15.
5. INTADC and INTSIO2 share the interrupt source level whose priority is 16.
3.4 Interrupt Sequence
An interrupt request, which raised interrupt latch, is held, until interrupt is accepted or interrupt latch is cleared to
“0” by resetting or an instruction. Interrupt acceptance sequence requires 8 machine cycles (2
s @16 MHz) after the
completion of the current instruction. The interrupt service task terminates upon execution of an interrupt return
instruction [RETI] (for maskable interrupts) or [RETN] (for non-maskable interrupts). Figure 3-1 shows the timing
chart of interrupt acceptance processing.
3.4.1 Interrupt acceptance processing is packaged as follows.
a. The interrupt master enable flag (IMF) is cleared to “0” in order to disable the acceptance of any fol-
lowing interrupt.
b. The interrupt latch (IL) for the interrupt source accepted is cleared to “0”.
c. The contents of the program counter (PC) and the program status word, including the interrupt master
enable flag (IMF), are saved (Pushed) on the stack in sequence of PSW + IMF, PCH, PCL. Mean-
while, the stack pointer (SP) is decremented by 3.
d. The entry address (Interrupt vector) of the corresponding interrupt service program, loaded on the vec-
tor table, is transferred to the program counter.
e. The instruction stored at the entry address of the interrupt service program is executed.
Note:When the contents of PSW are saved on the stack, the contents of IMF are also saved.
Interrupt source selector
INTSEL
(003EH)
76543
210
IL8ER
IL9ER
-
IL13ER
IL14ER
IL15ER
(Initial value: 00** *000)
IL8ER
Selects INTTBT or INT2
0: INTTBT
1: INT2
R/W
IL9ER
Selects INTTC1 or INT3
0: INTTC1
1: INT3
R/W
IL13ER
Selects INTSIO1 or INT4
0: INTSIO1
1: INT4
R/W
IL14ER
Selects INTTRX or INT5
0: INTTRX
1: INT5
R/W
IL15ER
Selects INTADC or INTSIO2
0: INTADC
1: INTSIO2
R/W