AT89C55WD-24JI Atmel, AT89C55WD-24JI Datasheet - Page 17

• Manufacturer Part Number: AT89C55WD-24JI
• Description: IC MICRO CTRL 24MHZ 44PLCC
• Manufacturer: Atmel
• Series: 89Cr

Specifications of AT89C55WD-24JI

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 24MHz
• Connectivity: UART/USART
• Peripherals: WDT
• Number Of I /o: 32
• Program Memory Size: 20KB (20K x 8)
• Program Memory Type: FLASH
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -
• Other names: AT89C55WD24JI

1921D–MICRO–6/08
The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in which the timers
overflow. The values are then polled by the circuitry in the next cycle. However, the Timer 2 flag,
TF2, is set at S2P2 and is polled in the same cycle in which the timer overflows.
Table 15-1.
Figure 15-1. Interrupt Sources
Symbol
EA
–
ET2
ES
ET1
EX1
ET0
EX0
User software should never write 1s to reserved bits, because they may be used in future AT89
products.
(MSB)
Enable Bit = 1 enables the interrupt.
Enable Bit = 0 disables the interrupt.
EA
Interrupt Enable (IE) Register
Position
IE.7
IE.6
IE.5
IE.4
IE.3
IE.2
IE.1
IE.0
–
EXF2
INT0
INT1
TF0
TF1
TF2
RI
TI
ET2
Function
Disables all interrupts. If EA = 0, no interrupt is acknowledged. If EA
= 1, each interrupt source is individually enabled or disabled by
setting or clearing its enable bit.
Reserved.
Timer 2 interrupt enable bit.
Serial Port interrupt enable bit.
Timer 1 interrupt enable bit.
External interrupt 1 enable bit.
Timer 0 interrupt enable bit.
External interrupt 0 enable bit.
0
1
0
1
ES
ET1
(LSB)
EX1
IE0
IE1
ET0
AT89C55WD
EX0
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