AT90CAN128-15AZ Atmel, AT90CAN128-15AZ Datasheet - Page 232

• Manufacturer Part Number: AT90CAN128-15AZ
• Description: MCU AVR 128K FLASH 15MHZ 64TQFP
• Manufacturer: Atmel
• Series: AVR® 90CANr

Specifications of AT90CAN128-15AZ

• Package / Case: 64-TQFP, 64-VQFP
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Speed: 16MHz
• Number Of I /o: 53
• Eeprom Size: 4K x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Program Memory Size: 128KB (128K x 8)
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: CAN, I²C, SPI, UART/USART
• Core Size: 8-Bit
• Processor Series: AT90CANx
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: CAN, SPI, UART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 53
• Number Of Timers: 4
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATDVK90CAN1, ATADAPCAN01
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 8 Channel
• Cpu Family: 90C
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 16MHz
• Total Internal Ram Size: 4KB
• # I/os (max): 53
• Number Of Timers - General Purpose: 4
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Pin Count: 64
• Package Type: TQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

18.9
232
Multi-master Systems and Arbitration
AT90CAN32/64/128
If multiple masters are connected to the same bus, transmissions may be initiated simulta-
neously by one or more of them. The TWI standard ensures that such situations are handled in
such a way that one of the masters will be allowed to proceed with the transfer, and that no data
will be lost in the process. An example of an arbitration situation is depicted below, where two
masters are trying to transmit data to a slave receiver.
Figure 18-20. An Arbitration Example
Several different scenarios may arise during arbitration, as described below:
• Two or more masters are performing identical communication with the same slave. In this
• Two or more masters are accessing the same slave with different data or direction bit. In this
• Two or more masters are accessing different slaves. In this case, arbitration will occur in the
case, neither the slave nor any of the masters will know about the bus contention.
case, arbitration will occur, either in the READ/WRITE bit or in the data bits. The masters
trying to output a one on SDA while another master outputs a zero will lose the arbitration.
Losing masters will switch to not addressed slave mode or wait until the bus is free and
transmit a new START condition, depending on application software action.
SLA bits. Masters trying to output a one on SDA while another master outputs a zero will lose
the arbitration. Masters losing arbitration in SLA will switch to slave mode to check if they are
being addressed by the winning master. If addressed, they will switch to SR or ST mode,
depending on the value of the READ/WRITE bit. If they are not being addressed, they will
switch to not addressed slave mode or wait until the bus is free and transmit a new START
condition, depending on application software action.
SDA
SCL
TRANSMITTER
Device 1
MASTER
Device 2
RECEIVER
SLAVE
Device 3
RECEIVER
SLAVE
........
Device n
R1
7679H–CAN–08/08
V
CC
R2