ATmega325 Atmel Corporation, ATmega325 Datasheet - Page 95

• Manufacturer Part Number: ATmega325
• Manufacturer: Atmel Corporation

Specifications of ATmega325

• Flash (kbytes): 32 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: 54
• Ext Interrupts: 17
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 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): 2
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

15.8
2570N–AVR–05/11
Timer/Counter Timing Diagrams
•
The Timer/Counter is a synchronous design and the timer clock (clk
clock enable signal in the following figures. The figures include information on when Interrupt
Flags are set.
shows the count sequence close to the MAX value in all modes other than phase correct PWM
mode.
Figure 15-8. Timer/Counter Timing Diagram, no Prescaling
Figure 15-9
Figure 15-9. Timer/Counter Timing Diagram, with Prescaler (f
Figure 15-10
Figure 15-10. Timer/Counter Timing Diagram, Setting of OCF0A, with Prescaler (f
The timer starts counting from a value higher than the one in OCR0A, and for that reason
misses the Compare Match and hence the OCn change that would have happened on the
way up.
TCNTn
TCNTn
TCNTn
(clk
(clk
(clk
OCRnx
OCFnx
TOVn
TOVn
clk
clk
clk
clk
clk
clk
I/O
I/O
I/O
I/O
I/O
I/O
Tn
Tn
Tn
/1)
/8)
/8)
shows the same timing data, but with the prescaler enabled.
shows the setting of OCF0A in all modes except CTC mode.
Figure 15-8
OCRnx - 1
MAX - 1
MAX - 1
contains timing data for basic Timer/Counter operation. The figure
OCRnx
MAX
MAX
ATmega325/3250/645/6450
OCRnx Value
OCRnx + 1
BOTTOM
BOTTOM
clk_I/O
/8)
T0
) is therefore shown as a
BOTTOM + 1
BOTTOM + 1
OCRnx + 2
clk_I/O
/8)
95