ATMEGA168-15AZ Atmel, ATMEGA168-15AZ Datasheet - Page 206
![MCU AVR 16K FLASH 15MHZ 32-TQFP](/photos/6/91/69154/313-32-tqfp_sml.jpg)
ATMEGA168-15AZ
Manufacturer Part Number
ATMEGA168-15AZ
Description
MCU AVR 16K FLASH 15MHZ 32-TQFP
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheet
1.ATMEGA168-15AZ.pdf
(340 pages)
Specifications of ATMEGA168-15AZ
Package / Case
32-TQFP, 32-VQFP
Voltage - Supply (vcc/vdd)
2.7 V ~ 5.5 V
Operating Temperature
-40°C ~ 125°C
Speed
16MHz
Number Of I /o
23
Eeprom Size
512 x 8
Core Processor
AVR
Program Memory Type
FLASH
Ram Size
1K x 8
Program Memory Size
16KB (16K x 8)
Data Converters
A/D 8x10b
Oscillator Type
Internal
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Connectivity
I²C, SPI, UART/USART
Core Size
8-Bit
Cpu Family
ATmega
Device Core
AVR
Device Core Size
8b
Frequency (max)
16MHz
Interface Type
2-Wire/USART/Serial
Total Internal Ram Size
1KB
# I/os (max)
23
Number Of Timers - General Purpose
3
Operating Supply Voltage (typ)
3.3/5V
Operating Supply Voltage (max)
5.5V
Operating Supply Voltage (min)
2.7V
On-chip Adc
8-chx10-bit
Instruction Set Architecture
RISC
Operating Temp Range
-40C to 125C
Operating Temperature Classification
Automotive
Mounting
Surface Mount
Pin Count
32
Package Type
TQFP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
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19.4
206
Multi-master Bus Systems, Arbitration and Synchronization
ATmega48/88/168 Automotive
The TWI protocol allows bus systems with several masters. Special concerns have been taken
in order to ensure that transmissions will proceed as normal, even if two or more masters initiate
a transmission at the same time. Two problems arise in multi-master systems:
The wired-ANDing of the bus lines is used to solve both these problems. The serial clocks from
all masters will be wired-ANDed, yielding a combined clock with a high 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 19-7. SCL Synchronization Between Multiple Masters
• An algorithm must be implemented allowing only one of the masters to complete the
• Different masters may use different SCL frequencies. A scheme must be devised to
transmission. All other masters should cease transmission when they discover that they have
lost the selection process. This selection process is called arbitration. When a contending
master discovers that it has lost the arbitration process, it should immediately switch to Slave
mode to check whether it is being addressed by the winning master. The fact that multiple
masters have started transmission at the same time should not be detectable to the slaves,
i.e. the data being transferred on the bus must not be corrupted.
synchronize the serial clocks from all masters, in order to let the transmission proceed in a
lockstep fashion. This will facilitate the arbitration process.
SCL from
SCL from
Master A
Master B
SCL Bus
Line
TA
Counting Low Period
low
Masters Start
TB
low
TA
Counting High Period
high
Masters Start
TB
high
7530I–AVR–02/10
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