ATTINY861A-SU Atmel, ATTINY861A-SU Datasheet - Page 50

• Manufacturer Part Number: ATTINY861A-SU
• Description: IC, MCU, 8BIT, 8K FLASH, 20SOIC
• Manufacturer: Atmel

Specifications of ATTINY861A-SU

• Controller Family/series: ATtiny
• No. Of I/o's: 16
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 512Byte
• Cpu Speed: 20MHz
• No.: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 8KB
• Oscillator Type: External, Internal
• Rohs Compliant: Yes

9.2.1
9.3
9.3.1
9.3.2
50
Register Description
ATtiny261A/461A/861A
Low Level Interrupt
MCUCR – MCU Control Register
GIMSK – General Interrupt Mask Register
A low level interrupt on INT0 is detected asynchronously. This means that the interrupt source
can be used for waking the part also from sleep modes other than Idle (the I/O clock is halted in
all sleep modes except Idle).
Note that if a level triggered interrupt is used for wake-up from Power-down, the required level
must be held long enough for the MCU to complete the wake-up to trigger the level interrupt. If
the level disappears before the end of the Start-up Time, the MCU will still wake up, but no inter-
rupt will be generated. The start-up time is defined by the SUT and CKSEL Fuses as described
in
If the low level on the interrupt pin is removed before the device has woken up then program
execution will not be diverted to the interrupt service routine but continue from the instruction fol-
lowing the SLEEP command.
The MCU Register contains control bits for interrupt sense control.
• Bits 1, 0 – ISC01, ISC00: Interrupt Sense Control 0 Bit 1 and Bit 0
The External Interrupt 0 is activated by the external pin INT0 or INT1 if the SREG I-flag and the
corresponding interrupt mask are set. The level and edges on the external INT0 or INT1 pin that
activate the interrupt are defined in
before detecting 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 inter-
rupt. 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 9-2.
• Bit 7 – INT1: External Interrupt Request 1 Enable
When the INT1 bit is set (one) and the I-bit in the Status Register (SREG) is set (one), the exter-
nal pin interrupt is enabled. The Interrupt Sense Control0 bits 1/0 (ISC01 and ISC00) in the MCU
Bit
0x35 (0x55)
Read/Write
Initial Value
Bit
0x3B (0x5B)
Read/Write
Initial Value
“Clock System” on page
ISC01
0
0
1
1
7
BODS
R/W
0
Interrupt 0 Sense Control
7
INT1
R/W
0
ISC00
0
1
0
1
6
PUD
R/W
0
6
INT0
R/W
0
Description
The low level of INT0 or INT1 generates an interrupt request.
Any logical change on INT0 or INT1 generates an interrupt request.
The falling edge of INT0 or INT1 generates an interrupt request.
The rising edge of INT0 or INT1 generates an interrupt request.
24.
5
SE
R/W
0
5
PCIE1
R/W
0
Table
4
SM1
R/W
0
4
PCIE0
R/w
0
9-2. The value on the INT0 or INT1 pin is sampled
3
SM0
R/W
0
3
–
R
0
2
BODSE
R/W
0
2
–
R
0
1
ISC01
R/W
0
1
–
R
0
0
ISC00
0
R/W
0
–
R
0
8197B–AVR–01/10
MCUCR
GIMSK