ATmega168A Atmel Corporation, ATmega168A Datasheet - Page 150
Manufacturer Part Number
Specifications of ATmega168A
Max. Operating Frequency
# Of Touch Channels
Hardware Qtouch Acquisition
Max I/o Pins
Adc Resolution (bits)
Adc Speed (ksps)
Resistive Touch Screen
Self Program Memory
Temp. Range (deg C)
-40 to 85
I/o Supply Class
1.8 to 5.5
Operating Voltage (vcc)
1.8 to 5.5
Mpu / Mmu
no / no
Output Compare Channels
Input Capture Channels
Calibrated Rc Oscillator
Compare Match Output Unit
The setup of the OC2x should be performed before setting the Data Direction Register for the
port pin to output. The easiest way of setting the OC2x value is to use the Force Output Com-
pare (FOC2x) strobe bit in Normal mode. The OC2x Register keeps its value even when
changing between Waveform Generation modes.
Be aware that the COM2x1:0 bits are not double buffered together with the compare value.
Changing the COM2x1:0 bits will take effect immediately.
The Compare Output mode (COM2x1:0) bits have two functions. The Waveform Generator uses
the COM2x1:0 bits for defining the Output Compare (OC2x) state at the next compare match.
Also, the COM2x1:0 bits control the OC2x pin output source.
schematic of the logic affected by the COM2x1:0 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 COM2x1:0 bits are shown. When referring to the
OC2x state, the reference is for the internal OC2x Register, not the OC2x pin.
Figure 18-4. Compare Match Output Unit, Schematic
The general I/O port function is overridden by the Output Compare (OC2x) from the Waveform
Generator if either of the COM2x1:0 bits are set. However, the OC2x 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 OC2x pin (DDR_OC2x) must be set as output before the OC2x value is visi-
ble on the pin. The port override function is independent of the Waveform Generation mode.
The design of the Output Compare pin logic allows initialization of the OC2x state before the out-
put is enabled. Note that some COM2x1:0 bit settings are reserved for certain modes of
”Register Description” on page 160
shows a simplified