ATtiny44A Atmel Corporation, ATtiny44A Datasheet - Page 75

• Manufacturer Part Number: ATtiny44A
• Manufacturer: Atmel Corporation

Specifications of ATtiny44A

• Flash (kbytes): 4 Kbytes
• Pin Count: 14
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 6
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 12
• Ext Interrupts: 12
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 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: Yes
• Crypto Engine: No
• Sram (kbytes): 0.25
• Eeprom (bytes): 256
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• 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: 2
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

8183D–AVR–04/11
PWM mode is shown in
shown as a histogram for illustrating the single-slope operation. The diagram includes non-
inverted and inverted PWM outputs. The small horizontal line marks on the TCNT0 slopes repre-
sent Compare Matches between OCR0x and TCNT0.
Figure 11-6.
The Timer/Counter Overflow Flag (TOV0) is set each time the counter reaches TOP. If the inter-
rupt is enabled, the interrupt handler routine can be used for updating the compare value.
In fast PWM mode, the compare unit allows generation of PWM waveforms on the OC0x pins.
Setting the COM0x[1:0] bits to two will produce a non-inverted PWM and an inverted PWM out-
put can be generated by setting the COM0x[1:0] to three: Setting the COM0A[1:0] bits to one
allowes the AC0A pin to toggle on Compare Matches if the WGM02 bit is set. This option is not
available for the OC0B pin (See
ible on the port pin if the data direction for the port pin is set as output. The PWM waveform is
generated by setting (or clearing) the OC0x Register at the Compare Match between OCR0x
and TCNT0, and clearing (or setting) the OC0x Register at the timer clock cycle the counter is
cleared (changes from TOP to BOTTOM).
The PWM frequency for the output can be calculated by the following equation:
The N variable represents the prescale factor (1, 8, 64, 256, or 1024).
The extreme values for the OCR0A Register represents special cases when generating a PWM
waveform output in the fast PWM mode. If the OCR0A is set equal to BOTTOM, the output will
be a narrow spike for each MAX+1 timer clock cycle. Setting the OCR0A equal to MAX will result
in a constantly high or low output (depending on the polarity of the output set by the COM0A[1:0]
bits.)
A frequency (with 50% duty cycle) waveform output in fast PWM mode can be achieved by set-
ting OC0x to toggle its logical level on each Compare Match (COM0x[1:0] = 1). The waveform
generated will have a maximum frequency of f
TCNTn
OCn
OCn
Period
1
Fast PWM Mode, Timing Diagram
2
Figure 11-6 on page
3
Table 11-3 on page
f
OCnxPWM
4
clk_I/O
75. The TCNT0 value is in the timing diagram
=
5
/2 when OCR0A is set to zero. This feature is
----------------- -
N 256
f
clk_I/O
79). The actual OC0x value will only be vis-
⋅
6
ATtiny24A/44A/84A
7
OCRnx Interrupt Flag Set
OCRnx Update and
TOVn Interrupt Flag Set
(COMnx[1:0] = 2)
(COMnx[1:0] = 3)
75