ATmega128A Atmel Corporation, ATmega128A Datasheet - Page 124

• 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

15.8
15.8.1
8151H–AVR–02/11
Compare Match Output Unit
Compare Output Mode and Waveform Generation
The Compare Output mode (COMnx1:0) bits have two functions. The waveform generator uses
the COMnx1:0 bits for defining the output compare (OCnx) state at the next compare match.
Secondly the COMnx1:0 bits control the OCnx pin output source.
schematic of the logic affected by the COMnx1:0 bit setting. The I/O registers, I/O bits, and I/O
pins in the figure are shown in bold. Only the parts of the general I/O port control registers (DDR
and PORT) that are affected by the COMnx1:0 bits are shown. When referring to the OCnx
state, the reference is for the internal OCnx Register, not the OCnx pin. If a system Reset occur,
the OCnx Register is reset to “0”.
Figure 15-5. Compare Match Output Unit, Schematic
The general I/O port function is overridden by the output compare (OCnx) from the Waveform
Generator if either of the COMnx1:0 bits are set. However, the OCnx pin direction (input or out-
put) is still controlled by the Data Direction Register (DDR) for the port pin. The data direction
register bit for the OCnx pin (DDR_OCnx) must be set as output before the OCnx value is visible
on the pin. The port override function is generally independent of the waveform generation
mode, but there are some exceptions. Refer to
details.
The design of the output compare pin logic allows initialization of the OCnx state before the out-
put is enabled. Note that some COMnx1:0 bit settings are reserved for certain modes of
operation.
The COMnx1:0 bits have no effect on the Input Capture unit.
The waveform generator uses the COMnx1:0 bits differently in normal, CTC, and PWM modes.
For all modes, setting the COMnx1:0 = 0 tells the waveform generator that no action on the
OCnx Register is to be performed on the next compare match. For compare output actions in the
non-PWM modes refer to
page
page
135, and for phase correct and phase and frequency correct PWM refer to
136.
See “Register Description” on page 134.
COMnx1
COMnx0
FOCnx
clk
I/O
Waveform
Generator
Table 15-2 on page
D
D
PORT
D
DDR
OCnx
135. For fast PWM mode refer to
Q
Q
Q
Table
15-2,
1
0
Table 15-3
Figure 15-5
ATmega128A
and
shows a simplified
OCnx
Pin
Table 15-4
Table 15-3 on
Table 15-4 on
124
for