atmega32u4-16mu ATMEL Corporation, atmega32u4-16mu Datasheet - Page 247

• Manufacturer Part Number: atmega32u4-16mu
• Description: Atmega32u4 8-bit Avr Microcontroller With 32k Bytes Of Isp Flash And Usb Controller
• Manufacturer: ATMEL Corporation

21.5
7766A–AVR–03/08
Overview of the TWI Module
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:
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.
The TWI module is comprised of several submodules, as shown in
drawn in a thick line are accessible through the AVR data bus.
• 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
Arbitration, SDA
Master A Loses
Figure
ATmega32U4
A
SDA
21-9. All registers
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