AT90CAN128-16AE ATMEL Corporation, AT90CAN128-16AE Datasheet - Page 15

• Manufacturer Part Number: AT90CAN128-16AE
• Description: 8-bit Avr Microcontroller With 128K Bytes of Isp Flash And CAN Controller.flash (Kbytes) 128 Vcc (V) 2.7-5.5 EEPROM (Kbytes) 4 SRAM (bytes) 4K CAN (mess. Obj.) 15
• Manufacturer: ATMEL Corporation

Interrupt Response Time
4250C–CAN–03/04
Note that the Status Register is not automatically stored when entering an interrupt rou-
tine, nor restored when returning from an interrupt routine. This must be handled by
software.
When using the CLI instruction to disable interrupts, the interrupts will be immediately
disabled. No interrupt will be executed after the CLI instruction, even if it occurs simulta-
neously with the CLI instruction. The following example shows how this can be used to
avoid interrupts during the timed EEPROM write sequence..
When using the SEI instruction to enable interrupts, the instruction following SEI will be
executed before any pending interrupts, as shown in this example.
The interrupt execution response for all the enabled AVR interrupts is four clock cycles
minimum. After four clock cycles the program vector address for the actual interrupt
handling routine is executed. During this four clock cycle period, the Program Counter is
pushed onto the Stack. The vector is normally a jump to the interrupt routine, and this
jump takes three clock cycles. If an interrupt occurs during execution of a multi-cycle
instruction, this instruction is completed before the interrupt is served. If an interrupt
occurs when the MCU is in sleep mode, the interrupt execution response time is
increased by four clock cycles. This increase comes in addition to the start-up time from
the selected sleep mode.
Assembly Code Example
C Code Example
Assembly Code Example
C Code Example
in
cli
sbi EECR, EEMWE
sbi EECR, EEWE
out SREG, r16
char cSREG;
cSREG = SREG;
/* disable interrupts during timed sequence */
_CLI();
EECR |= (1<<EEMWE); /* start EEPROM write */
EECR |= (1<<EEWE);
SREG = cSREG;
sei
sleep ; enter sleep, waiting for interrupt
; note: will enter sleep before any pending
; interrupt(s)
_SEI(); /* set Global Interrupt Enable */
_SLEEP(); /* enter sleep, waiting for interrupt */
/* note: will enter sleep before any pending interrupt(s) */
r16, SREG
; set Global Interrupt Enable
; store SREG value
; disable interrupts during timed sequence
; start EEPROM write
; restore SREG value (I-bit)
/* store SREG value */
/* restore SREG value (I-bit) */
AT90CAN128
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