ATA6603-EK Atmel, ATA6603-EK Datasheet - Page 168

• Manufacturer Part Number: ATA6603-EK
• Description: MCU, MPU & DSP Development Tools Demoboard LIN-MCM
• Manufacturer: Atmel

Specifications of ATA6603-EK

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

168
ATA6602/ATA6603
Figure 4-58. Fast PWM Mode, Timing Diagram
The Timer/Counter Overflow Flag (TOV2) 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 OC2x pin.
Setting the COM2x1:0 bits to two will produce a non-inverted PWM and an inverted PWM output
can be generated by setting the COM2x1:0 to three. TOP is defined as 0xFF when WGM2:0 = 3,
and OCR2A when MGM2:0 = 7 (see
be visible on the port pin if the data direction for the port pin is set as output. The PWM wave-
form is generated by setting (or clearing) the OC2x Register at the compare match between
OCR2x and TCNT2, and clearing (or setting) the OC2x 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, 32, 64, 128, 256, or 1024).
The extreme values for the OCR2A Register represent special cases when generating a PWM
waveform output in the fast PWM mode. If the OCR2A is set equal to BOTTOM, the output will
be a narrow spike for each MAX+1 timer clock cycle. Setting the OCR2A equal to MAX will result
in a constantly high or low output (depending on the polarity of the output set by the COM2A1:0
bits.)
A frequency (with 50% duty cycle) waveform output in fast PWM mode can be achieved by set-
ting OC2x to toggle its logical level on each compare match (COM2x1:0 = 1). The waveform
generated will have a maximum frequency of f
ture is similar to the OC2A toggle in CTC mode, except the double buffer feature of the Output
Compare unit is enabled in the fast PWM mode.
f
OCnxPWM
Period
TCNTn
OCn
OCn
=
-------------------- -
N
f
clk_I/O
1
256
2
3
Table 4-59 on page
4
oc2
5
= f
clk_I/O
6
/2 when OCR2A is set to zero. This fea-
172). The actual OC2x value will only
7
(COMnx1:0 = 2)
(COMnx1:0 = 3)
TOVn Interrupt Flag Set
OCRnx Interrupt
OCRnx Update and
Flag Set
4921E–AUTO–09/09