ATmega8535 Atmel Corporation, ATmega8535 Datasheet - Page 118

• Manufacturer Part Number: ATmega8535
• Manufacturer: Atmel Corporation

Specifications of ATmega8535

• Flash (kbytes): 8 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 32
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

Registers
Definitions
Timer/Counter Clock
Sources
118
ATmega8535(L)
The Timer/Counter (TCNT2) and Output Compare Register (OCR2) are 8-bit registers.
Interrupt request (shorten as Int.Req.) signals are all visible in the Timer Interrupt Flag
Register (TIFR). All interrupts are individually masked with the Timer Interrupt Mask
Register (TIMSK). TIFR and TIMSK are not shown in the figure since these registers are
shared by other timer units.
The Timer/Counter can be clocked internally, via the prescaler, or asynchronously
clocked from the TOSC1/2 pins, as detailed later in this section. The asynchronous
operation is controlled by the Asynchronous Status Register (ASSR). The Clock Select
logic block controls which clock source the Timer/Counter uses to increment (or decre-
ment) its value. The Timer/Counter is inactive when no clock source is selected. The
output from the Clock Select logic is referred to as the timer clock (clk
The double buffered Output Compare Register (OCR2) is compared with the
Timer/Counter value at all times. The result of the compare can be used by the Wave-
form Generator to generate a PWM or variable frequency output on the Output Compare
Pin (OC2). See “Output Compare Unit” on page 119 for details. The Compare Match
event will also set the Compare Flag (OCF2) which can be used to generate an output
compare interrupt request.
Many register and bit references in this section are written in general form. A lower case
“n” replaces the Timer/Counter number, in this case 2. However, when using the register
or bit defines in a program, the precise form must be used (i.e., TCNT2 for accessing
Timer/Counter2 counter value and so on).
The definitions in Table 50 are also used extensively throughout this section.
Table 50. Definitions
The Timer/Counter can be clocked by an internal synchronous or an external asynchro-
nous clock source. The clock source clk
When the AS2 bit in the ASSR Register is written to logic one, the clock source is taken
from the Timer/Counter Oscillator connected to TOSC1 and TOSC2. For details on
asynchronous operation, see “Asynchronous Status Register – ASSR” on page 131. For
details on clock sources and prescaler, see “Timer/Counter Prescaler” on page 134.
BOTTOM
MAX
TOP
The counter reaches the BOTTOM when it becomes zero (0x00).
The counter reaches its MAXimum when it becomes 0xFF (decimal 255).
The counter reaches the TOP when it becomes equal to the highest
value in the count sequence. The TOP value can be assigned to be the
fixed value 0xFF (MAX) or the value stored in the OCR2 Register. The
assignment is dependent on the mode of operation.
T2
is by default equal to the MCU clock, clk
T2
).
2502K–AVR–10/06
I/O
.