ATtiny43U Atmel Corporation, ATtiny43U Datasheet - Page 106

• Manufacturer Part Number: ATtiny43U
• Manufacturer: Atmel Corporation

Specifications of ATtiny43U

• Flash (kbytes): 4 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 8 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 16
• Ext Interrupts: 16
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 4
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.25
• Eeprom (bytes): 64
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 0.7 to 5.5
• Operating Voltage (vcc): 0.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

14.3.5
106
ATtiny43U
Start Condition Detector
If the slave is not able to receive more data it does not acknowledge the data byte it has last
received. When the master does a read operation it must terminate the operation by forcing the
acknowledge bit low after the last byte transmitted.
The start condition detector is shown in
to 300 ns) to ensure valid sampling of the SCL line. The start condition detector is only enabled
in two-wire mode.
Figure 14-6. Start Condition Detector, Logic Diagram
The start condition detector works asynchronously and can therefore wake up the processor
from power-down sleep mode. However, the protocol used might have restrictions on the SCL
hold time. Therefore, when using this feature the oscillator start-up time (set by CKSEL fuses,
see
of the USISIF bit on
2. In addition, the start detector will hold the SCL line low after the master has forced a
3. The master set the first bit to be transferred and releases the SCL line (C). The slave
4. After eight bits containing slave address and data direction (read or write) have been
5. When the slave is addressed, it holds the SDA line low during the acknowledgment
6. Multiple bytes can now be transmitted, all in same direction, until a stop condition is
“Clock Sources” on page
detects the start condition and sets the USISIF Flag. The flag can generate an interrupt
if necessary.
negative edge on this line (B). This allows the slave to wake up from sleep or complete
other tasks before setting up the USI Data Register to receive the address. This is done
by clearing the start condition flag and resetting the counter.
samples the data and shifts it into the USI Data Register at the positive edge of the SCL
clock.
transferred, the slave counter overflows and the SCL line is forced low (D). If the slave
is not the one the master has addressed, it releases the SCL line and waits for a new
start condition.
cycle before holding the SCL line low again (i.e., the USI Counter Register must be set
to 14 before releasing SCL at (D)). Depending on the R/W bit the master or slave
enables its output. If the bit is set, a master read operation is in progress (i.e., the slave
drives the SDA line) The slave can hold the SCL line low after the acknowledge (E).
given by the master (F), or a new start condition is given.
Write( USISIF)
page 112
SDA
SCL
24) must also be taken into consideration. Refer to the description
for further details.
Figure
14-6. The SDA line is delayed (in the range of 50
D Q
CLR
D Q
CLR
USISIF
CLOCK
HOLD
8048B–AVR–03/09