A000047 Arduino, A000047 Datasheet - Page 133

• Manufacturer Part Number: A000047
• Description: MCU, MPU & DSP Development Tools Mega2560
• Manufacturer: Arduino
• Series: -r
• Type: MCUr

Specifications of A000047

• Processor To Be Evaluated: ATmega2560
• Interface Type: USB, I2C, SPI
• Dimensions: 4 in x 2.1 in
• Operating Supply Voltage: 5 V
• Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ATmega2560

15.9.3
15.9.4
15.9.5
2549M–AVR–09/10
TCNT0 – Timer/Counter Register
OCR0A – Output Compare Register A
OCR0B – Output Compare Register B
Table 15-9.
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 OCR0x Registers.
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.
The Output Compare Register B 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 OC0B pin.
Bit
0x26 (0x46)
Read/Write
Initial Value
Bit
0x27 (0x47)
Read/Write
Initial Value
Bit
0x28 (0x48)
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/W
7
0
7
0
7
0
CS00
0
1
0
1
0
1
0
1
R/W
R/W
R/W
6
0
6
0
6
0
ATmega640/1280/1281/2560/2561
R/W
R/W
R/W
5
0
5
0
5
0
External clock source on T0 pin. Clock on falling edge.
External clock source on T0 pin. Clock on rising edge.
No clock source (Timer/Counter stopped)
R/W
R/W
R/W
4
0
4
0
4
0
OCR0A[7:0]
OCR0B[7:0]
TCNT0[7:0]
clk
clk
clk
clk
I/O
I/O
clk
I/O
R/W
R/W
R/W
I/O
/1024 (From prescaler)
3
0
3
0
3
0
/256 (From prescaler)
I/O
/64 (From prescaler)
/8 (From prescaler)
Description
/(No prescaling)
R/W
R/W
R/W
2
0
2
0
2
0
R/W
R/W
R/W
1
0
1
0
1
0
R/W
R/W
R/W
0
0
0
0
0
0
OCR0A
OCR0B
TCNT0
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