AT90PWM2-16SQ View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
AT90PWM2-16SQ
Atmel Corporation
'AT90PWM2-16SQ' PDF : 365 Pages View PDF
AT90PWM2/3/2B/3B
• Bits 1:0 – WGM01:0: Waveform Generation Mode
Combined with the WGM02 bit found in the TCCR0B Register, these bits control the counting
sequence of the counter, the source for maximum (TOP) counter value, and what type of wave-
form generation to be used, see Table 14-8. Modes of operation supported by the Timer/Counter
unit are: Normal mode (counter), Clear Timer on Compare Match (CTC) mode, and two types of
Pulse Width Modulation (PWM) modes (see “Modes of Operation” on page 92).
Table 14-8. Waveform Generation Mode Bit Description
Mode
WGM02
WGM01
WGM00
Timer/Count
er Mode of
Operation
TOP
0
0
0
0
Normal
0xFF
1
0
0
1
PWM, Phase
Correct
0xFF
2
0
1
0
CTC
OCRA
3
0
1
1
Fast PWM
0xFF
4
1
0
0
Reserved
–
5
1
0
1
PWM, Phase
Correct
OCRA
6
1
1
0
Reserved
–
7
1
1
1
Fast PWM
OCRA
Update of
OCRx at
Immediate
TOP
Immediate
TOP
–
TOP
–
TOP
TOV Flag
Set on(1)(2)
MAX
BOTTOM
MAX
MAX
–
BOTTOM
–
TOP
14.8.2
Notes: 1. MAX = 0xFF
2. BOTTOM = 0x00
Timer/Counter Control Register B – TCCR0B
Bit
7
6
5
FOC0A
FOC0B
–
Read/Write
W
W
R
Initial Value
0
0
0
4
3
2
1
0
–
WGM02
CS02
CS01
CS00
TCCR0B
R
R
R
R/W
R/W
0
0
0
0
0
• Bit 7 – FOC0A: Force Output Compare A
The FOC0A bit is only active when the WGM bits specify a non-PWM mode.
However, for ensuring compatibility with future devices, this bit must be set to zero when
TCCR0B is written when operating in PWM mode. When writing a logical one to the FOC0A bit,
an immediate Compare Match is forced on the Waveform Generation unit. The OC0A output is
changed according to its COM0A1:0 bits setting. Note that the FOC0A bit is implemented as a
strobe. Therefore it is the value present in the COM0A1:0 bits that determines the effect of the
forced compare.
A FOC0A strobe will not generate any interrupt, nor will it clear the timer in CTC mode using
OCR0A as TOP.
The FOC0A bit is always read as zero.
• Bit 6 – FOC0B: Force Output Compare B
The FOC0B bit is only active when the WGM bits specify a non-PWM mode.
However, for ensuring compatibility with future devices, this bit must be set to zero when
TCCR0B is written when operating in PWM mode. When writing a logical one to the FOC0B bit,
an immediate Compare Match is forced on the Waveform Generation unit. The OC0B output is
4317K–AVR–03/2013
100
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