A000046 Arduino, A000046 Datasheet - Page 220

• Manufacturer Part Number: A000046
• Description: MCU, MPU & DSP Development Tools Uno
• Manufacturer: Arduino
• Series: -r
• Type: MCUr

Specifications of A000046

• Processor To Be Evaluated: ATmega328
• Interface Type: USB, I2C, SPI
• Dimensions: 2.7 in x 2.1 in
• Operating Supply Voltage: 5 V
• Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ATmega328

8161D–AVR–10/09
Figure 21-8. Arbitration Between Two Masters
Note that arbitration is not allowed between:
• A REPEATED START condition and a data bit.
• A STOP condition and a data bit.
• A REPEATED START and a STOP condition.
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.
Synchronized
SCL Line
SDA from
SDA from
Master A
Master B
SDA Line
START
ATmega48PA/88PA/168PA/328P
Arbitration, SDA
Master A Loses
A
SDA
220