Datasheet

177

2466T–AVR–07/10

ATmega16(L)

Figure 83. 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