ATmega8HVA Atmel Corporation, ATmega8HVA Datasheet - Page 85

• Manufacturer Part Number: ATmega8HVA
• Manufacturer: Atmel Corporation

Specifications of ATmega8HVA

• Flash (kbytes): 8 Kbytes
• Pin Count: 28
• Max. Operating Frequency: 4 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 3
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 6
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 6
• Adc Resolution (bits): 12
• Adc Speed (ksps): 1.9
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 256
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -20 to 85
• I/o Supply Class: 1.8 to 9.0
• Operating Voltage (vcc): 1.8 to 9.0
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 4
• Input Capture Channels: 2
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

17.7.1
17.7.2
17.8
8024A–AVR–04/08
Timer/Counter Timing Diagrams
Compare Match Blocking by TCNT0 Write
Using the Output Compare Unit
All CPU write operations to the TCNTnH/L Register will block any Compare Match that occur in
the next timer clock cycle, even when the timer is stopped. This feature allows OCRnB/A to be
initialized to the same value as TCNTn without triggering an interrupt when the Timer/Counter
clock is enabled.
Since writing TCNTnH/L will block all Compare Matches for one timer clock cycle, there are risks
involved when changing TCNTnH/L when using the Output Compare Unit, independently of
whether the Timer/Counter is running or not. If the value written to TCNTnH/L equals the
OCRnB/A value, the Compare Match will be missed.
The Timer/Counter is a synchronous design and the timer clock (clk
clock enable signal in the following figures. The figures include information on when Interrupt
Flags are set.
The figure shows the count sequence close to the MAX value.
Figure 17-6. Timer/Counter Timing Diagram, no Prescaling
Figure 17-7 on page 85
Figure 17-7. Timer/Counter Timing Diagram, with Prescaler (f
Figure 17-8 on page 86
TCNTn
TCNTn
(clk
(clk
TOVn
TOVn
clk
clk
clk
clk
I/O
I/O
I/O
Tn
I/O
Tn
/1)
/8)
Figure 17-6 on page 85
shows the same timing data, but with the prescaler enabled.
shows the setting of OCFnA and OCFnB in Normal mode.
MAX - 1
MAX - 1
contains timing data for basic Timer/Counter operation.
MAX
MAX
ATmega8HVA/16HVA
BOTTOM
BOTTOM
clk_I/O
/8)
Tn
) is therefore shown as a
BOTTOM + 1
BOTTOM + 1
85