AT90CAN64 Atmel Corporation, AT90CAN64 Datasheet - Page 147

• 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

14.2.1
14.3
14.4
7679H–CAN–08/08
Timer/Counter Clock Sources
Counter Unit
Definitions
The following definitions are used extensively throughout the section:
The Timer/Counter can be clocked by an internal synchronous or an external asynchronous
clock source. The clock source is selected by the clock select logic which is controlled by the
clock select (CS22:0) bits located in the Timer/Counter control register (TCCR2).The clock
source clk
is written to logic one, the clock source is taken from the Timer/Counter Oscillator connected to
TOSC1 and TOSC2 or directly from TOSC1. For details on asynchronous operation, see
chronous Status Register – ASSR” on page
“Timer/Counter2 Prescaler” on page
The main part of the 8-bit Timer/Counter is the programmable bi-directional counter unit.
14-2
Figure 14-2. Counter Unit Block Diagram
Figure 14-3.
Signal description (internal signals):
BOTTOM
MAX
TOP
shows a block diagram of the counter and its surrounding environment.
count
direction
clear
clk
top
bottom
T2
T2
is by default equal to the MCU clock, clk
The counter reaches the BOTTOM when it becomes zero (0x00).
The counter reaches its MAXimum when it becomes 0xFF (decimal 255).
The counter reaches the TOP when it becomes equal to the highest value in the
count sequence. The TOP value can be assigned to be the fixed value 0xFF
(MAX) or the value stored in the OCR2A Register. The assignment is depen-
dent on the mode of operation.
DATA BUS
TCNTn
Increment or decrement TCNT2 by 1.
Selects between increment and decrement.
Clear TCNT2 (set all bits to zero).
Timer/Counter clock.
Signalizes that TCNT2 has reached maximum value.
Signalizes that TCNT2 has reached minimum value (zero).
direction
163.
count
clear
bottom
Control Logic
160. For details on clock sources and prescaler, see
top
TOVn
(Int.Req.)
I/O
clk
Tn
. When the AS2 bit in the ASSR Register
Prescaler
AT90CAN32/64/128
clk
TnS
Oscillator
T/C
clk
I/O
“Asyn-
Figure
TOSC2
TOSC1
147