ATTINY85-15ST1 Atmel, ATTINY85-15ST1 Datasheet - Page 69

• Manufacturer Part Number: ATTINY85-15ST1
• Description: MCU AVR 8K FLASH 15MHZ 8-SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY85-15ST1

• Package / Case: 8-SOIC (3.9mm Width)
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 105°C
• Speed: 16MHz
• Number Of I /o: 6
• Eeprom Size: 512 x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 512 x 8
• Program Memory Size: 8KB (8K x 8)
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: USI
• Core Size: 8-Bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

12.6.4
7598H–AVR–07/09
Phase Correct PWM Mode
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 COM0A1:0 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 (COM0x1:0 = 1). The waveform
generated will have a maximum frequency of f
feature is similar to the OC0A toggle in CTC mode, except the double buffer feature of the Out-
put Compare unit is enabled in the fast PWM mode.
The phase correct PWM mode (WGM02:0 = 1 or 5) provides a high resolution phase correct
PWM waveform generation option. The phase correct PWM mode is based on a dual-slope
operation. The counter counts repeatedly from BOTTOM to TOP and then from TOP to BOT-
TOM. TOP is defined as 0xFF when WGM2:0 = 1, and OCR0A when WGM2:0 = 5. In
non-inverting Compare Output mode, the Output Compare (OC0x) is cleared on the Compare
Match between TCNT0 and OCR0x while upcounting, and set on the Compare Match while
down-counting. 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 symmetric feature of the dual-slope PWM modes, these modes are preferred for motor con-
trol applications.
In phase correct PWM mode the counter is incremented until the counter value matches TOP.
When the counter reaches TOP, it changes the count direction. The TCNT0 value will be equal
to TOP for one timer clock cycle. The timing diagram for the phase correct PWM mode is shown
on
the dual-slope operation. The diagram includes non-inverted and inverted PWM outputs. The
small horizontal line marks on the TCNT0 slopes represent Compare Matches between OCR0x
and TCNT0.
Figure 12-7. Phase Correct PWM Mode, Timing Diagram
Figure
TCNTn
OCn
OCn
Period
12-7. The TCNT0 value is in the timing diagram shown as a histogram for illustrating
1
2
OC0
= f
clk_I/O
/2 when OCR0A is set to zero. This
3
ATtiny25/45/85
OCnx Interrupt Flag Set
OCRnx Update
TOVn Interrupt Flag Set
(COMnx1:0 = 2)
(COMnx1:0 = 3)
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