ATTINY25-20SUR Atmel, ATTINY25-20SUR Datasheet - Page 83

• Manufacturer Part Number: ATTINY25-20SUR
• Description: MCU AVR 2KB FLASH 20MHZ 8SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY25-20SUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 6
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

11.9.4
11.9.5
2586M–AVR–07/10
TCNT0 – Timer/Counter Register
OCR0A – Output Compare Register A
The FOC0B bit is always read as zero.
• Bits 5:4 – Res: Reserved Bits
These bits are reserved bits in the ATtiny25/45/85 and will always read as zero.
• Bit 3 – WGM02: Waveform Generation Mode
See the description in the
• Bits 2:0 – CS0[2:0]: Clock Select
The three Clock Select bits select the clock source to be used by the Timer/Counter.
Table 11-6.
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 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.
Bit
0x32
Read/Write
Initial Value
Bit
0x29
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
7
0
7
0
CS00
0
1
0
1
0
1
0
1
R/W
R/W
“TCCR0A – Timer/Counter Control Register A” on page
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
5
0
5
0
R/W
R/W
4
0
4
0
OCR0A[7:0]
TCNT0[7:0]
R/W
R/W
3
0
3
0
R/W
R/W
2
0
2
0
R/W
R/W
1
0
1
0
R/W
R/W
0
0
0
0
80.
OCR0A
TCNT0
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