ATMEGA48-20PI Atmel, ATMEGA48-20PI Datasheet - Page 66

• Manufacturer Part Number: ATMEGA48-20PI
• Description: IC AVR MCU 4K 5V 20MHZ 28-DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA48-20PI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 6x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: ATMEGA48-24PI; ATMEGA48-24PI

12.2
12.2.1
66
Register Description
ATmega48/88/168
EICRA – External Interrupt Control Register A
The External Interrupt Control Register A contains control bits for interrupt sense control.
• Bit 7..4 – Res: Reserved Bits
These bits are unused bits in the ATmega48/88/168, and will always read as zero.
• Bit 3, 2 – ISC11, ISC10: Interrupt Sense Control 1 Bit 1 and Bit 0
The External Interrupt 1 is activated by the external pin INT1 if the SREG I-flag and the corre-
sponding interrupt mask are set. The level and edges on the external INT1 pin that activate the
interrupt are defined in
edges. If edge or toggle interrupt is selected, pulses that last longer than one clock period will
generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt. If low level
interrupt is selected, the low level must be held until the completion of the currently executing
instruction to generate an interrupt.
Table 12-1.
• Bit 1, 0 – ISC01, ISC00: Interrupt Sense Control 0 Bit 1 and Bit 0
The External Interrupt 0 is activated by the external pin INT0 if the SREG I-flag and the corre-
sponding interrupt mask are set. The level and edges on the external INT0 pin that activate the
interrupt are defined in
edges. If edge or toggle interrupt is selected, pulses that last longer than one clock period will
generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt. If low level
interrupt is selected, the low level must be held until the completion of the currently executing
instruction to generate an interrupt.
Table 12-2.
Bit
(0x69)
Read/Write
Initial Value
ISC11
ISC01
0
0
1
1
0
0
1
1
Interrupt 1 Sense Control
Interrupt 0 Sense Control
ISC10
ISC00
R
7
–
0
0
1
0
1
0
1
0
1
Table
Table
Description
The low level of INT1 generates an interrupt request.
Any logical change on INT1 generates an interrupt request.
The falling edge of INT1 generates an interrupt request.
The rising edge of INT1 generates an interrupt request.
Description
The low level of INT0 generates an interrupt request.
Any logical change on INT0 generates an interrupt request.
The falling edge of INT0 generates an interrupt request.
The rising edge of INT0 generates an interrupt request.
R
6
–
0
12-1. The value on the INT1 pin is sampled before detecting
12-2. The value on the INT0 pin is sampled before detecting
R
5
–
0
R
4
–
0
ISC11
R/W
3
0
ISC10
R/W
2
0
ISC01
R/W
1
0
ISC00
R/W
0
0
2545S–AVR–07/10
EICRA