AT89LP6440 Atmel Corporation, AT89LP6440 Datasheet - Page 41

• Manufacturer Part Number: AT89LP6440
• Manufacturer: Atmel Corporation

Specifications of AT89LP6440

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 38
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 153.8
• Sram (kbytes): 4.25
• Eeprom (bytes): 8192
• Self Program Memory: IAP
• Operating Voltage (vcc): 2.4 to 3.6
• Timers: 3
• Isp: SPI/OCD
• Watchdog: Yes

9.1
3706C–MICRO–2/11
Interrupt Response Time
Table 9-1.
The interrupt flags may be set by their hardware in any clock cycle. The interrupt controller polls
the flags in the last clock cycle of the instruction in progress. If one of the flags was set in the
preceding cycle, the polling cycle will find it and the interrupt system will generate an LCALL to
the appropriate service routine as the next instruction, provided that the interrupt is not blocked
by any of the following conditions: an interrupt of equal or higher priority level is already in prog-
ress; the instruction in progress is RETI or any write to the IE, IP, IPH, IE2, IP2 or IP2H registers;
the CPU is currently forced into idle by an IAP or FDATA write. Each of these conditions will
block the generation of the LCALL to the interrupt service routine. The second condition ensures
that if the instruction in progress is RETI or any access to IE, IP, IPH, IE2, IP2 or IP2H, then at
least one more instruction will be executed before any interrupt is vectored to. The polling cycle
is repeated at the last cycle of each instruction, and the values polled are the values that were
present at the previous clock cycle. If an active interrupt flag is not being serviced because of
one of the above conditions and is no longer active when the blocking condition is removed, the
denied interrupt will not be serviced. In other words, the fact that the interrupt flag was once
active but not serviced is not remembered. Every polling cycle is new.
If a request is active and conditions are met for it to be acknowledged, a hardware subroutine
call to the requested service routine will be the next instruction executed. The call itself takes
four cycles. Thus, a minimum of five complete clock cycles elapsed between activation of an
interrupt request and the beginning of execution of the first instruction of the service routine. A
longer response time results if the request is blocked by one of the previously listed conditions. If
an interrupt of equal or higher priority level is already in progress, the additional wait time
depends on the nature of the other interrupt's service routine. If the instruction in progress is not
in its final clock cycle, the additional wait time cannot be more than 8 cycles, since the longest
instruction is 9 cycles long. If the instruction in progress is RETI with XSTK, the additional wait
time cannot be more than 14 cycles (a maximum of 5 more cycles to complete the instruction in
progress, plus a maximum of 9 cycles to complete the next instruction). Thus, in a single-inter-
Interrupt
System Reset
External Interrupt 0
Timer 0 Overflow
External Interrupt 1
Timer 1 Overflow
Serial Port Interrupt
Timer 2 Interrupt
Analog Comparator Interrupt
General-purpose Interrupt
Compare/Capture Array Interrupt
Serial Peripheral Interface Interrupt
ADC Interrupt
Two-Wire Interface Interrupt
Interrupt Vector Addresses
Source
RST or POR or BOD
IE0
TF0
IE1
TF1
RI or TI
TF2 or EXF2
CFA or CFB
GPIF
T2CCF
SPIF or MODF or TXE
ADIF
TWIF
7-0
3-0
AT89LP3240/6440
Vector Address
000BH
001BH
002BH
003BH
004BH
005BH
0000H
0003H
0013H
0023H
0033H
0043H
0053H
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