Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller VQFN 32 (5x5) 8-Bit 16 MHz I/O number 22

101

102

103

104

105

106

107

108

109

110

106

7799D–AVR–11/10

ATmega8U2/16U2/32U2

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.

15.9.3 TCNT0 – Timer/Counter Register

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.

15.9.4 OCR0A – Output Compare Register A

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.

15.9.5 OCR0B – Output Compare Register B

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.

15.9.6 TIMSK0 – Timer/Counter Interrupt Mask Register

• Bits 7:3 – Res: Reserved Bits

These bits are reserved bits and will always read as zero.

1 0 0 clk

I/O

/256 (From prescaler)

1 0 1 clk

I/O

/1024 (From prescaler)

1 1 0 External clock source on T0 pin. Clock on falling edge.

1 1 1 External clock source on T0 pin. Clock on rising edge.

Table 15-9. Clock Select Bit Description (Continued)

CS02 CS01 CS00 Description

Bit 76543210

0x26 (0x46) TCNT0[7:0] TCNT0

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 0

Bit 76543210

0x27 (0x47) OCR0A[7:0] OCR0A

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 0

Bit 76543210

0x28 (0x48) OCR0B[7:0] OCR0B

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 0

Bit 76543 2 10

(0x6E) – – – – – OCIE0B OCIE0A TOIE0 TIMSK0

Read/Write R R R R R R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 0