ATtiny26 Atmel Corporation, ATtiny26 Datasheet - Page 90

• Manufacturer Part Number: ATtiny26
• Manufacturer: Atmel Corporation

Specifications of ATtiny26

• Flash (kbytes): 2 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 16
• Ext Interrupts: 11
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.12
• Eeprom (bytes): 128
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 3
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

Start Condition
Detector
Alternative USI
Usage
Half-duplex
Asynchronous Data
Transfer
4-bit Counter
12-bit Timer/Counter
Edge Triggered
External Interrupt
Software Interrupt
90
ATtiny26(L)
The start condition detector is shown in Figure 49. The SDA line is delayed (in the range of 50 to
300 ns) to ensure valid sampling of the SCL line. The start condition detector is only enabled in
Two-wire mode.
When Two-wire mode is selected, the USISIF flag is set (to one) when a start condition is
detected. When output disable mode or Three-wire mode is selected and (USICSx = 0b11 &
USICLK = 0) or (USICS = 0b10 & USICLK = 0), any edge on the SCK pin sets the flag.
The start condition detector is working asynchronously and can therefore wake up the processor
from the Power-down sleep mode. However, the protocol used might have restrictions on the
SCL hold time. Therefore, when using this feature in this case the oscillator start-up time set by
the CKSEL Fuses (see “Clock Systems and their Distribution” on page 23) must also be taken
into the consideration. Refer to the description of “Bit 7 – USISIF: Start Condition Interrupt Flag”
on page 81 for further details.
When the USI unit is not used for serial communication, it can be set up to do alternative tasks
due to its flexible design.
By utilizing the Shift Register in Three-wire mode, it is possible to implement a more compact
and higher performance UART than by software only.
The 4-bit counter can be used as a stand-alone counter with overflow interrupt. Note that if the
counter is clocked externally, both clock edges will generate an increment.
Combining the USI 4-bit counter and Timer/Counter0 allows them to be used as a 12-bit
counter.
By setting the counter to maximum value (F) it can function as an additional external interrupt.
The overflow flag and interrupt enable bit are then used for the external interrupt. This feature is
selected by the USICS1 bit.
The counter overflow interrupt can be used as a software interrupt triggered by a clock strobe.
1477K–AVR–08/10