ATmega48 Atmel Corporation, ATmega48 Datasheet - Page 156

• Manufacturer Part Number: ATmega48
• Manufacturer: Atmel Corporation

Specifications of ATmega48

• Flash (kbytes): 4 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 24
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 256
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

18.11.2
2545T–AVR–05/11
TCCR2B – Timer/counter control register B
Table 18-8.
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 6 – FOC2B: Force output compare B
The FOC2B 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 FOC2B bit,
an immediate Compare Match is forced on the Waveform Generation unit. The OC2B output is
changed according to its COM2B1:0 bits setting. Note that the FOC2B bit is implemented as a
strobe. Therefore it is the value present in the COM2B1:0 bits that determines the effect of the
forced compare.
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
0
1
0
1
0
1
0
1
R
5
–
0
Timer/counter
phase correct
phase correct
operation
Fast PWM
Fast PWM
Reserved
Reserved
mode of
Normal
R
4
–
0
PWM,
PWM,
CTC
WGM22
R
3
0
OCRA
OCRA
OCRA
0xFF
0xFF
0xFF
TOP
ATmega48/88/168
CS22
–
–
R
2
0
Immediate
Immediate
Update of
BOTTOM
BOTTOM
OCRx at
CS21
R/W
1
0
TOP
TOP
–
–
CS20
R/W
0
0
set on
BOTTOM
BOTTOM
TOV flag
MAX
MAX
MAX
TOP
TCCR2B
–
–
(1)(2)
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