ATMEGA32-16PU Atmel, ATMEGA32-16PU Datasheet - Page 170

• Manufacturer Part Number: ATMEGA32-16PU
• Description: IC AVR MCU 32K 16MHZ 5V 40DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA32-16PU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Processor Series: ATMEGA32x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 2 KB
• Interface Type: 2-Wire/SPI/USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3
• Operating Supply Voltage: 4.5 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8-ch x 10-bit
• A/d Inputs: 8-Channel, 10-Bit
• Cpu Speed: 16 MIPS
• Eeprom Memory: 1K Bytes
• Input Output: 32
• Interface: 2-Wire/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin PDIP
• Programmable Memory: 32K Bytes
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 4.5-5.5 V
• Data Rom Size: 1024 B
• Height: 4.83 mm
• Length: 52.58 mm
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 4.5 V
• Width: 13.97 mm
• Controller Family/series: AVR MEGA
• No. Of I/o's: 32
• Eeprom Memory Size: 1024Byte
• Ram Memory Size: 2KB
• Rohs Compliant: Yes
• For Use With: ATSTK524 - KIT STARTER ATMEGA32M1/MEGA32C1ATSTK600-TQFP32 - STK600 SOCKET/ADAPTER 32-TQFPATSTK600-TQFP44 - STK600 SOCKET/ADAPTER 44-TQFPATSTK600-DIP40 - STK600 SOCKET/ADAPTER 40-PDIP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRDRAGON - KIT DRAGON 32KB FLASH MEM AVRATAVRISP2 - PROGRAMMER AVR IN SYSTEMATJTAGICE2 - AVR ON-CHIP D-BUG SYSTEMATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Combining Address and Data
Packets into a Transmission
Multi-master Bus
Systems, Arbitration and
Synchronization
170
ATmega32(L)
any more bytes, it should inform the transmitter by sending a NACK after the final byte.
The MSB of the data byte is transmitted first.
Figure 80. Data Packet Format
A transmission basically consists of a START condition, a SLA+R/W, one or more data
packets and a STOP condition. An empty message, consisting of a START followed by
a STOP condition, is illegal. Note that the wired-ANDing of the SCL line can be used to
implement handshaking between the master and the slave. The slave can extend the
SCL low period by pulling the SCL line low. This is useful if the clock speed set up by the
master is too fast for the slave, or the slave needs extra time for processing between the
data transmissions. The slave extending the SCL low period will not affect the SCL high
period, which is determined by the master. As a consequence, the slave can reduce the
TWI data transfer speed by prolonging the SCL duty cycle.
Figure 81 shows a typical data transmission. Note that several data bytes can be trans-
mitted between the SLA+R/W and the STOP condition, depending on the software
protocol implemented by the application software.
Figure 81. Typical Data Transmission
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-mas-
ter systems:
•
SDA
SCL
Transmitter
Aggregate
SDA from
SDA from
SCL from
receiverR
Master
SDA
An algorithm must be implemented allowing only one of the masters to complete the
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.
START
SLA+R/W
Addr MSB
1
2
Data MSB
SLA+R/W
1
Addr LSB
7
R/W
2
8
ACK
9
Data Byte
7
Data MSB
Data LSB
1
8
2
Data Byte
ACK
9
7
Data LSB
8
STOP, REPEATED
ACK
2503G–AVR–11/04
9
START or Next
Data Byte
STOP