ATmega48 Atmel Corporation, ATmega48 Datasheet - Page 99

• Manufacturer Part Number: ATmega48
• Manufacturer: Atmel Corporation

Specifications of ATmega48

• Flash (kbytes): 4 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 24
• 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): 0.5
• Eeprom (bytes): 256
• Self Program Memory: NO
• 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: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

15.8
2545T–AVR–05/11
Timer/counter timing diagrams
• The timer starts counting from a value higher than the one in OCRnx, and for that reason
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 on page 100
except CTC mode and PWM mode, where OCR0A is TOP.
symmetry around BOTTOM the OCnx value at MAX must correspond to the result of an up-
counting Compare Match
misses the Compare Match and hence the OCnx change that would have happened on the
way up
TCNTn
TCNTn
(clk
(clk
TOVn
TOVn
clk
clk
clk
clk
I/O
I/O
I/O
Tn
I/O
Tn
/1)
/8)
shows the same timing data, but with the prescaler enabled.
Figure 15-8
MAX - 1
MAX - 1
contains timing data for basic Timer/Counter operation. The figure
shows the setting of OCF0B in all modes and OCF0A in all modes
MAX
MAX
clk_I/O
ATmega48/88/168
BOTTOM
BOTTOM
/8).
T0
) is therefore shown as a
BOTTOM + 1
BOTTOM + 1
99