ATMEGA644P-A15MZ Atmel, ATMEGA644P-A15MZ Datasheet - Page 156

• Manufacturer Part Number: ATMEGA644P-A15MZ
• Description: MCU AVR 64KB FLASH 16MHZ 44QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA644P-A15MZ

• Package / Case: 44-VQFN Exposed Pad
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Speed: 16MHz
• Number Of I /o: 32
• Eeprom Size: 2K x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Program Memory Size: 64KB (64K x 8)
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: I²C, SPI, UART/USART
• Core Size: 8-Bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

15.11.2
156
ATmega164P/324P/644P
TCCR2B – Timer/Counter Control Register B
• Bits 1:0 – WGM21:0: Waveform Generation Mode
Combined with the WGM22 bit found in the TCCR2B 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 15-8.
Notes:
• Bit 7 – FOC2A: Force Output Compare A
The FOC2A 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
TCCR2B is written when operating in PWM mode. When writing a logical one to the FOC2A bit,
an immediate Compare Match is forced on the Waveform Generation unit. The OC2A output is
changed according to its COM2A1:0 bits setting. Note that the FOC2A bit is implemented as a
strobe. Therefore it is the value present in the COM2A1:0 bits that determines the effect of the
forced compare.
A FOC2A strobe will not generate any interrupt, nor will it clear the timer in CTC mode using
OCR2A as TOP.
The FOC2A bit is always read as zero.
Bit
(0xB1)
Read/Write
Initial Value
Mode
0
1
2
3
4
5
6
7
1. MAX= 0xFF
2. BOTTOM= 0x00
WGM2
0
0
0
0
1
1
1
1
Waveform Generation Mode Bit Description
FOC2A
W
7
0
WGM1
0
0
1
1
0
0
1
1
FOC2B
W
6
0
WGM0
Table
0
1
0
1
0
1
0
1
R
5
–
0
15-8. Modes of operation supported by the Timer/Counter
Timer/Counter
Mode of
Operation
Normal
PWM, Phase
Correct
CTC
Fast PWM
Reserved
PWM, Phase
Correct
Reserved
Fast PWM
“Modes of Operation” on page
R
4
–
0
WGM22
R/W
3
0
OCRA
OCRA
OCRA
0xFF
0xFF
0xFF
TOP
CS22
–
–
R/W
2
0
Immediate
Immediate
Update of
BOTTOM
BOTTOM
OCRx at
CS21
R/W
1
0
TOP
TOP
–
–
145).
CS20
R/W
0
0
7674F–AVR–09/09
Set on
TOV Flag
BOTTOM
BOTTOM
MAX
MAX
MAX
TOP
TCCR2B
–
–
(1)(2)