ATMEGA8535L-8AC Atmel, ATMEGA8535L-8AC Datasheet - Page 73

• Manufacturer Part Number: ATMEGA8535L-8AC
• Description: IC AVR MCU 8K LV 8MHZ COM 44TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8535L-8AC

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Output Compare Unit
2502K–AVR–10/06
Depending of the mode of operation used, the counter is cleared, incremented, or dec-
remented at each timer clock (clk
clock source, selected by the Clock Select bits (CS02:0). When no clock source is
selected (CS02:0 = 0) the timer is stopped. However, the TCNT0 value can be accessed
by the CPU, regardless of whether clk
priority over) all counter clear or count operations.
The counting sequence is determined by the setting of the WGM01 and WGM00 bits
located in the Timer/Counter Control Register (TCCR0). There are close connections
between how the counter behaves (counts) and how waveforms are generated on the
output compare output OC0. For more details about advanced counting sequences and
waveform generation, see “Modes of Operation” on page 76.
The Timer/Counter Overflow Flag (TOV0) is set according to the mode of operation
selected by the WGM01:0 bits. TOV0 can be used for generating a CPU interrupt.
The 8-bit comparator continuously compares TCNT0 with the Output Compare Register
(OCR0). Whenever TCNT0 equals OCR0, the comparator signals a match. A match will
set the Output Compare Flag (OCF0) at the next timer clock cycle. If enabled (OCIE0 =
1 and Global Interrupt Flag in SREG is set), the Output Compare Flag generates an out-
put compare interrupt. The OCF0 Flag is automatically cleared when the interrupt is
executed. Alternatively, the OCF0 Flag can be cleared by software by writing a logical
one to its I/O bit location. The Waveform Generator uses the match signal to generate
an output according to operating mode set by the WGM01:0 bits and Compare Output
mode (COM01:0) bits. The max and bottom signals are used by the Waveform Genera-
tor for handling the special cases of the extreme values in some modes of operation
(See “Modes of Operation” on page 76.).
Figure 29 shows a block diagram of the output compare unit.
Figure 29. Output Compare Unit, Block Diagram
top
bottom
Signalize that TCNT0 has reached maximum value.
Signalize that TCNT0 has reached minimum value (zero).
bottom
FOCn
top
OCRn
T0
Waveform Generator
WGMn1:0
=
). clk
(8-bit Comparator )
DATA BUS
T0
T0
is present or not. A CPU write overrides (has
can be generated from an external or internal
COMn1:0
TCNTn
OCFn (Int.Req.)
ATmega8535(L)
OCn
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