AT90USB1286-16MU ATMEL [ATMEL Corporation], AT90USB1286-16MU Datasheet - Page 114

• Manufacturer Part Number: AT90USB1286-16MU
• Description: Microcontroller with 64/128K Bytes of ISP Flash and USB Controller
• Manufacturer: ATMEL [ATMEL Corporation]

13.8.2
114
AT90USB64/128
Timer/Counter Control Register B – TCCR0B
Note:
• Bits 3, 2 – Res: Reserved Bits
These bits are reserved bits in the AT90USB64/128 and will always read as zero.
• 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
unit are: Normal mode (counter), Clear Timer on Compare Match (CTC) mode, and two types of
Pulse Width Modulation (PWM) modes (see
Table 13-7.
Notes:
• 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.
Bit
Read/Write
Initial Value
Mode
0
1
2
3
4
5
6
7
1. A special case occurs when OCR0B equals TOP and COM0B1 is set. In this case, the Com-
1. MAX
2. BOTTOM = 0x00
WGM2
pare Match is ignored, but the set or clear is done at TOP. See
page 109
0
0
0
0
1
1
1
1
7
FOC0A
W
0
Waveform Generation Mode Bit Description
WGM1
for more details.
= 0xFF
0
0
1
1
0
0
1
1
6
FOC0B
W
0
WGM0
0
1
0
1
0
1
0
1
5
–
R
0
Table
Timer/Counter
Mode of
Operation
Normal
PWM, Phase
Correct
CTC
Fast PWM
Reserved
PWM, Phase
Correct
Reserved
Fast PWM
13-7. Modes of operation supported by the Timer/Counter
4
–
R
0
“Modes of Operation” on page
3
WGM02
R/W
0
OCRA
OCRA
OCRA
0xFF
0xFF
0xFF
TOP
2
CS02
R/W
0
–
–
Update of
Immediate
Immediate
OCRx at
1
CS01
R/W
0
TOP
TOP
TOP
TOP
“Phase Correct PWM Mode” on
–
–
0
CS00
R/W
0
106).
Set on
TOV Flag
BOTTOM
BOTTOM
MAX
MAX
MAX
TOP
–
–
TCCR0B
(1)(2)
7593A–AVR–02/06