ATMEGA168-15AZ Atmel, ATMEGA168-15AZ Datasheet - Page 207

• Manufacturer Part Number: ATMEGA168-15AZ
• Description: MCU AVR 16K FLASH 15MHZ 32-TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA168-15AZ

• Package / Case: 32-TQFP, 32-VQFP
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Speed: 16MHz
• Number Of I /o: 23
• Eeprom Size: 512 x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 1K x 8
• Program Memory Size: 16KB (16K x 8)
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: I²C, SPI, UART/USART
• Core Size: 8-Bit
• Cpu Family: ATmega
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 16MHz
• Interface Type: 2-Wire/USART/Serial
• Total Internal Ram Size: 1KB
• # I/os (max): 23
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 8-chx10-bit
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Pin Count: 32
• Package Type: TQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7530I–AVR–02/10
Arbitration is carried out by all masters continuously monitoring the SDA line after outputting
data. If the value read from the SDA line does not match the value the Master had output, it has
lost the arbitration. Note that a Master can only lose arbitration when it outputs a high SDA value
while another Master outputs a low value. The losing Master should immediately go to Slave
mode, checking if it is being addressed by the winning Master. The SDA line should be left high,
but losing masters are allowed to generate a clock signal until the end of the current data or
address packet. Arbitration will continue until only one Master remains, and this may take many
bits. If several masters are trying to address the same Slave, arbitration will continue into the
data packet.
Figure 19-8. Arbitration Between Two Masters
Note that arbitration is not allowed between:
It is the user software’s responsibility to ensure that these illegal arbitration conditions never
occur. This implies that in multi-master systems, all data transfers must use the same composi-
tion of SLA+R/W and data packets. In other words: All transmissions must contain the same
number of data packets, otherwise the result of the arbitration is undefined.
• A REPEATED START condition and a data bit.
• A STOP condition and a data bit.
• A REPEATED START and a STOP condition.
Synchronized
SCL Line
SDA from
SDA from
Master A
Master B
SDA Line
START
ATmega48/88/168 Automotive
Arbitration, SDA
Master A Loses
A
SDA
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