DS89C420_02 Datasheet, PDF (34/58 Pages) Maxim Integrated Products – Ultra-High-Speed Microcontroller

Table 12. INTERRUPT SUMMARY
DS89C420
INTERRUPT
VECTOR
NATURAL
ORDER
FLAG
ENABLE
PRIORITY
CONTROL
Power-Fail
0
33h
PFI (WDCON.4) EPFI(WDCON.5) N/A
(Highest)
External Interrupt 0
03h
1
IE0 (TCON.1)** EX0 (IE.0)
LPX0 (IP0.0)
MPX0 (IP1.0)
Timer 0 Overflow
0Bh
2
TF0 (TCON.5)* ET0 (IE.1)
LPT0 (IP0.1)
MPT0 (IP 1.1)
External Interrupt 1
13h
3
IE1 (TCON.3)** EX1 (IE.2)
LPX1 (IP0.2)
MPX1 (IP1.2)
Timer 1 Overflow
1Bh
4
TF1 (TCON.7)* ET1 (IE.3)
LPT1 (IP0.3)
MPT1 (IP1.3)
Serial Port 0
RI_0 (SCON0.0)
LPS0 (IP0.4)
23h
5
ES0 (IE.4)
TI_0 (SCON0.1)
MPS0 (IP1.4)
Timer 2 Overflow
2Bh
6
TF2 (T2CON.7) _{ET2 (IE.5)}
EXF2 (T2CON.6)
LPT2 (IP0.5)
MPT2 (IP1.5)
Serial Port 1
RI_1 (SCON1.0)
LPS1 (IP0.6)
3Bh
7
ES1 (IE.6)
TI_1 (SCON1.1)
MPS1 (IP1.6)
External Interrupt 2
43h
8
IE2 (EXIF.4)
EX2 (EIE.0)
LPX2 (EIP0.0)
MPX2 (EIP1.0)
External Interrupt 3
4Bh
9
IE3 (EXIF.5)
EX3 (EIE.1)
LPX3 (EIP0.1)
MPX3 (EIP1.1)
External Interrupt 4
53h
10
IE4 (EXIF.6)
EX4 (EIE.2)
LPX4 (EIP0.2)
MPX4 (EIP1.2)
External Interrupt 5
5Bh
11
IE5 (EXIF.7)
EX5 (EIE.3)
LPX5 (EIP0.3)
MPX5 (EIP1.3)
Watchdog
63h
12
WDIF (WDCON.3) EWDI (EIE.4)
LPWDI (EIP0.4)
(Lowest)
MPWDI (EIP1.4)
*Cleared automatically by hardware when the service routine is vectored to.
**If the interrupt is edge triggered, cleared automatically by hardware when the service routine is vectored to. If
the interrupt is level triggered, the flag follows the state of the pin.
The processor indicates that an interrupt condition occurred by setting the respective flag bit. This bit is
set regardless of whether the interrupt is enabled or disabled. Unless marked in Table 12, all of these flags
must be cleared by software.
TIMER/COUNTERS
Three 16-bit timers are incorporated in the DS89C420. All three timers can be used as either counters of
external events, where 1-to-0 transitions on a port pin are monitored and counted, or timers that count
oscillator cycles. Table 13 summarizes the timer functions.
Timers 0 and 1 both have three modes of operations. They can each be used as a 13-bit timer/counter, a
16-bit timer/counter, or an 8-bit timer/counter with auto-reload. Timer 0 has a fourth operating mode as
two 8-bit timer/counters without auto-reload. Each timer can also be used as a counter of external pulses
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