AT90CAN64 Atmel Corporation, AT90CAN64 Datasheet - Page 214

• Manufacturer Part Number: AT90CAN64
• Manufacturer: Atmel Corporation

Specifications of AT90CAN64

• Flash (kbytes): 64 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 8
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 2
• Can: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 4
• Eeprom (bytes): 2048
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 8
• Input Capture Channels: 2
• Pwm Channels: 7
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

18.6.4
18.6.5
214
AT90CAN32/64/128
TWI Data Register – TWDR
TWI (Slave) Address Register – TWAR
• Bits 1.0 – TWPS: TWI Prescaler Bits
These bits can be read and written, and control the bit rate prescaler.
Table 18-2.
To calculate bit rates, see
in the equation.
In Transmit mode, TWDR contains the next byte to be transmitted. In receive mode, the TWDR
contains the last byte received. It is writable while the TWI is not in the process of shifting a byte.
This occurs when the TWI interrupt flag (TWINT) is set by hardware. Note that the Data Register
cannot be initialized by the user before the first interrupt occurs. The data in TWDR remains sta-
ble as long as TWINT is set. While data is shifted out, data on the bus is simultaneously shifted
in. TWDR always contains the last byte present on the bus, except after a wake up from a sleep
mode by the TWI interrupt. In this case, the contents of TWDR is undefined. In the case of a lost
bus arbitration, no data is lost in the transition from Master to Slave. Handling of the ACK bit is
controlled automatically by the TWI logic, the CPU cannot access the ACK bit directly.
• Bits 7.0 – TWD: TWI Data Register
These eight bits constitute the next data byte to be transmitted, or the latest data byte received
on the TWI Serial Bus.
• Bits 7.1 – TWA: TWI (Slave) Address Register
These seven bits constitute the slave address of the TWI unit. The TWAR should be loaded with
the 7-bit slave address to which the TWI will respond when programmed as a slave transmitter
or receiver, and not needed in the master modes. In multimaster systems, TWAR must be set in
masters which can be addressed as slaves by other masters.
• Bit 0 – TWGCE: TWI General Call Recognition Enable Bit
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
TWPS1
0
0
1
1
TWD7
TWA6
TWI Bit Rate Prescaler
R/W
R/W
7
1
7
1
TWD6
TWA5
R/W
R/W
6
1
6
1
“Bit Rate Generator Unit” on page
TWD5
TWA4
R/W
R/W
5
1
5
1
TWPS0
0
1
0
1
TWD4
TWA3
R/W
R/W
4
1
4
1
TWD3
TWA2
R/W
R/W
3
1
3
1
Prescaler Value
1
4
16
64
TWD2
TWA1
R/W
R/W
2
1
2
1
210. The value of TWPS1.0 is used
TWD1
TWA0
R/W
R/W
1
1
1
1
TWGCE
TWD0
R/W
R/W
0
1
0
0
TWDR
TWAR
7679H–CAN–08/08