ATmega128A Atmel Corporation, ATmega128A Datasheet - Page 164

• Manufacturer Part Number: ATmega128A
• Manufacturer: Atmel Corporation

Specifications of ATmega128A

• Flash (kbytes): 128 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
• 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): 4096
• 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

18.2.1
8151H–AVR–02/11
Timing Example
Figure 18-2. Output Compare Modulator, Schematic
When the modulator is enabled the type of modulation (logical AND or OR) can be selected by
the PORTB7 Register. Note that the DDRB7 controls the direction of the port independent of the
COMnx1:0 bit setting.
Figure 18-3
ate in fast PWM mode (non-inverted) and Timer/Counter2 uses CTC waveform mode with toggle
Compare Output mode (COMnx1:0 = 1).
Figure 18-3. Output Compare Modulator, Timing Diagram
In this example, Timer/Counter2 provides the carrier, while the modulating signal is generated
by the Output Compare unit C of the Timer/Counter1.
The resolution of the PWM signal (OC1C) is reduced by the modulation. The reduction factor is
equal to the number of system clock cycles of one period of the carrier (OC2). In this example
the resolution is reduced by a factor of two. The reason for the reduction is illustrated in
18-3
high time is one cycle longer than the period 3 high time, but the result on the PB7 output is
equal in both periods.
(FPWM Mode)
(PORTB7 = 0)
(PORTB7 = 1)
at the second and third period of the PB7 output when PORTB7 equals zero. The period 2
( From Waveform Generator )
( From Waveform Generator )
COM21
COM20
COM1C1
COM1C0
(CTC Mode)
(Period)
OC1C
clk
OC2
PB7
PB7
illustrates the modulator in action. In this example the Timer/Counter1 is set to oper-
I/O
PORTB7
D
OC1C
D
D
OC2
Q
Q
Q
1
DATABUS
Modulator
2
0
1
DDRB7
D
Q
1
0
ATmega128A
3
Vcc
OC2 / PB7
OC1C /
Pin
Figure
164