ATMEGA8535L-8AC Atmel, ATMEGA8535L-8AC Datasheet - Page 178

• Manufacturer Part Number: ATMEGA8535L-8AC
• Description: IC AVR MCU 8K LV 8MHZ COM 44TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8535L-8AC

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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ATmega8535(L)
period equal to the one from the Master with the shortest high period. The low period of
the combined clock is equal to the low period of the Master with the longest low period.
Note that all masters listen to the SCL line, effectively starting to count their SCL high
and low time-out periods when the combined SCL line goes high or low, respectively.
Figure 82. SCL Synchronization Between Multiple Masters
Arbitration is carried out by all masters continuously monitoring the SDA line after out-
putting 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 83. Arbitration Between Two Masters
Synchronized
SCL Line
SDA From
SDA From
SCL From
SCL From
Master A
Master B
Master A
Master B
SDA Line
SCL Bus
Line
START
TA
Counting Low Period
low
Masters Start
TB
low
Arbitration, SDA
Master A Loses
TA
Counting High Period
high
A
Masters Start
TB
SDA
high
2502K–AVR–10/06