ATmega328P datasheet(212/345 Pages) ATMEL

Part #	ATmega328P

Description	8-bit Microcontroller with 32K Bytes In-System Programmable Flash

PDF	345 Pages

Scroll/Zoom	100%

Manufacturer	ATMEL [ATMEL Corporation]

Direct Link	http://www.atmel.com

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7810A–AVR–11/09

ATmega328P [Preliminary]

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 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.

SDA from

Master A

SDA from

Master B

SDA Line

Synchronized

SCL Line

START

Master A Loses

Arbitration, SDA

SDA

ATmega328P Datasheet(PDF) 212 Page - ATMEL Corporation