EasyManuals Logo

Atmel ATtiny25 User Manual

Atmel ATtiny25
196 pages
To Next Page IconTo Next Page
To Next Page IconTo Next Page
To Previous Page IconTo Previous Page
To Previous Page IconTo Previous Page
Page #75 background imageLoading...
Page #75 background image
75
7598H–AVR–07/09
ATtiny25/45/85
Notes: 1. MAX = 0xFF
2. BOTTOM = 0x00
12.8.2 Timer/Counter Control Register B – TCCR0B
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
changed according to its COM0B1:0 bits setting. Note that the FOC0B bit is implemented as a
strobe. Therefore it is the value present in the COM0B1:0 bits that determines the effect of the
forced compare.
Table 12-7. Waveform Generation Mode Bit Description
Mode WGM2 WGM1 WGM0
Timer/Counter
Mode of
Operation TOP
Update of
OCRx at
TOV Flag
Set on
(1)(2)
0 0 0 0 Normal 0xFF Immediate MAX
10 0 1
PWM, Phase
Correct
0xFF TOP BOTTOM
2 0 1 0 CTC OCRA Immediate MAX
3 0 1 1 Fast PWM 0xFF TOP MAX
4 1 0 0 Reserved
51 0 1
PWM, Phase
Correct
OCRA TOP BOTTOM
6 1 1 0 Reserved
7 1 1 1 Fast PWM OCRA TOP TOP
Bit 7 6 5 4 3 2 1 0
FOC0A FOC0B WGM02 CS02 CS01 CS00 TCCR0B
Read/Write W W R R R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0

Table of Contents

Questions and Answers:

Question and Answer IconNeed help?

Do you have a question about the Atmel ATtiny25 and is the answer not in the manual?

Atmel ATtiny25 Specifications

General IconGeneral
BrandAtmel
ModelATtiny25
CategoryMicrocontrollers
LanguageEnglish

Related product manuals