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AT90S8414
Preliminary
4-25
Address
Labels
Code
Comments
$000
rjmp
RESET
; Reset Handle
$001
rjmp
EXT_INT0
; IRQ0 Handle
$002
rjmp
EXT_INT1
; IRQ1 Handle
$003
rjmp
TIM1_CAPT
; Timer1 capture Handle
$004
rjmp
TIM1_COMPA
; Timer1 compareA Handle
$005
rjmp
TIM1_COMPB
; Timer1 compareB Handle
$006
rjmp
TIM1_OVF
; Timer1 overflow Handle
$007
rjmp
TIM0_COMP
; Timer0 compare Handle
$008
rjmp
TIM0_OVF
; Timer0 overflow Handle
$009
rjmp
SPI_HANDLE
; SPI TX Handle
$00a
rjmp
UART_RXC
; UART RX Complete Handle
$00b
rjmp
UART_DRE
; UDR Empty Handle
$00c
rjmp
UART_TXC
; UART TX Complete Handle
$00d
rjmp
ANA_COMP
; Analog Comparator Handle
;
$00e
MAIN:
<instr> xxx
; Main program start
…
…
…
…
RESET SOURCES
The AT90S2312 has three sources of reset:
·
Power-On Reset. The MCU is reset when a supply voltage is applied to the VCC and GND pins.
·
External Reset. The MCU is reset when a low level is present on the RESET pin for more than two XTAL cycles
·
Watchdog Reset. The MCU is reset when the Watchdog timer period expires and the Watchdog is enabled.
During reset, all I/O registers are then set to their initial values, and the program starts execution from address $000. The
instruction placed in address $000 must be an RJMP - relative jump - instruction to the reset handling routine. If the
program never enables an interrupt source, the interrupt vectors are not used, and regular program code can be placed at
these locations. The circuit diagram in Figure 25 shows the reset logic. Table 3 defines the timing and electrical
parameters of the reset circuitry.
Figure 25: Reset Logic
Table 3: Reset Characteristics
Symbol
Parameter
Min
Typ
Max
Units
V
POT
Power-On Reset Threshold Voltage
1.8
2
2.2
V
V
RST
RESET Pin Threshold Voltage
VCC/2
V
T
POR
Power-On Reset Period
2
3
4
ms
T
TOUT
Reset Delay Time-Out Period
11
16
21
ms