ATMEGA3250P-20AUR Atmel, ATMEGA3250P-20AUR Datasheet - Page 104

• Manufacturer Part Number: ATMEGA3250P-20AUR
• Description: MCU AVR 32K FLASH 20MHZ 100TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA3250P-20AUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 69
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

14.10.2
14.10.3
14.10.4
104
ATmega325P/3250P
TCNT0 – Timer/Counter Register
OCR0A – Output Compare Register A
TIMSK0 – Timer/Counter 0 Interrupt Mask Register
• Bit 2:0 – CS02:0: Clock Select
The three Clock Select bits select the clock source to be used by the Timer/Counter.
Table 14-6.
If external pin modes are used for the Timer/Counter0, transitions on the T0 pin will clock the
counter even if the pin is configured as an output. This feature allows software control of the
counting.
The Timer/Counter Register gives direct access, both for read and write operations, to the
Timer/Counter unit 8-bit counter. Writing to the TCNT0 Register blocks (removes) the compare
match on the following timer clock. Modifying the counter (TCNT0) while the counter is running,
introduces a risk of missing a compare match between TCNT0 and the OCR0A Register.
The Output Compare Register A contains an 8-bit value that is continuously compared with the
counter value (TCNT0). A match can be used to generate an Output Compare interrupt, or to
generate a waveform output on the OC0A pin.
Bit
0x26 (0x46)
Read/Write
Initial Value
Bit
0x27 (0x47)
Read/Write
Initial Value
Bit
(0x6E)
Read/Write
Initial Value
CS02
0
0
0
0
1
1
1
1
CS01
0
0
1
1
0
0
1
1
Clock Select Bit Description
R/W
R/W
R
7
0
7
–
0
7
0
CS00
0
1
0
1
0
1
0
1
R/W
R/W
R
6
–
0
6
0
6
0
Description
No clock source (Timer/Counter stopped)
clk
clk
clk
clk
clk
External clock source on T0 pin. Clock on falling edge.
External clock source on T0 pin. Clock on rising edge.
I/O
I/O
I/O
I/O
I/O
/(No prescaling)
/8 (From prescaler)
/64 (From prescaler)
/256 (From prescaler)
/1024 (From prescaler)
R/W
R/W
R
5
–
0
5
0
5
0
R/W
R/W
R
4
–
0
4
0
4
0
OCR0A[7:0]
TCNT0[7:0]
R/W
R/W
R
3
–
0
3
0
3
0
R/W
R/W
R
2
–
0
2
0
2
0
OCIE0A
R/W
R/W
R/W
1
0
1
0
1
0
TOIE0
R/W
R/W
R/W
0
0
0
0
0
0
8023F–AVR–07/09
TIMSK0
TCNT0
OCR0