ATmega16A Atmel Corporation, ATmega16A Datasheet - Page 125

• Manufacturer Part Number: ATmega16A
• Manufacturer: Atmel Corporation

Specifications of ATmega16A

• Flash (kbytes): 16 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 32
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• 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): 1
• Eeprom (bytes): 512
• 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: 3
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

8154B–AVR–07/09
The counter counts repeatedly from BOTTOM to MAX and then from MAX to BOTTOM. In non-
inverting Compare Output mode, the Output Compare (OC2) is cleared on the compare match
between TCNT2 and OCR2 while upcounting, and set on the compare match while downcount-
ing. In inverting Output Compare mode, the operation is inverted. The dual-slope operation has
lower maximum operation frequency than single slope operation. However, due to the symmet-
ric feature of the dual-slope PWM modes, these modes are preferred for motor control
applications.
The PWM resolution for the phase correct PWM mode is fixed to 8 bits. In phase correct PWM
mode the counter is incremented until the counter value matches MAX. When the counter
reaches MAX, it changes the count direction. The TCNT2 value will be equal to MAX for one
timer clock cycle. The timing diagram for the phase correct PWM mode is shown on
The TCNT2 value is in the timing diagram shown as a histogram for illustrating the dual-slope
operation. The diagram includes non-inverted and inverted PWM outputs. The small horizontal
line marks on the TCNT2 slopes represent compare matches between OCR2 and TCNT2.
Figure 17-7. Phase Correct PWM Mode, Timing Diagram
The Timer/Counter Overflow Flag (
Interrupt Flag can be used to generate an interrupt each time the counter reaches the BOTTOM
value.
In phase correct PWM mode, the compare unit allows generation of PWM waveforms on the
OC2 pin. Setting the COM21:0 bits to 2 will produce a non-inverted PWM. An inverted PWM out-
put can be generated by setting the COM21:0 to 3 (see
OC2 value will only be visible on the port pin if the data direction for the port pin is set as output.
The PWM waveform is generated by clearing (or setting) the OC2 Register at the compare
match between OCR2 and TCNT2 when the counter increments, and setting (or clearing) the
OC2 Register at compare match between OCR2 and TCNT2 when the counter decrements. The
PWM frequency for the output when using phase correct PWM can be calculated by the follow-
ing equation:
TCNTn
OCn
OCn
Period
1
TOV2
f
OCnPCPWM
) is set each time the counter reaches BOTTOM. The
2
=
----------------- -
N 510
f
clk_I/O
⋅
Table 17-5 on page
3
OCn Interrupt Flag Set
OCRn Update
TOVn Interrupt Flag Set
(COMn1:0 = 2)
(COMn1:0 = 3)
ATmega16A
132). The actual
Figure
17-7.
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