ATMEGA8HVD-4MX Atmel, ATMEGA8HVD-4MX Datasheet - Page 71

• Manufacturer Part Number: ATMEGA8HVD-4MX
• Description: MCU AVR 8K FLASH 2.1-8V 4MHZ QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8HVD-4MX

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 4MHz
• Peripherals: POR, WDT
• Number Of I /o: 5
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 2.4 V
• Data Converters: A/D 1x10b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 85°C
• Package / Case: 18-MLF® Exposed Pad (Staggered Leads), DFN
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32ATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Connectivity: -

15. Timer/Counter0 and Timer/Counter1 Prescalers
15.1
15.2
15.3
8052B–AVR–09/08
Overview
Internal Clock Source
Prescaler Reset
Timer/Counter1 and Timer/Counter0 share the same prescaler module, but the Timer/Coun-
ters can have different prescaler settings. The description below applies to both
Timer/Counter1 and Timer/Counter0.
The Timer/Counter can be clocked directly by the system clock (by setting the CSn2:0 = 1).
This provides the fastest operation, with a maximum Timer/Counter clock frequency equal to
system clock frequency (f
used as a clock source. The prescaled clock has a frequency of either f
f
The prescaler is free running, i.e., operates independently of the Clock Select logic of the
Timer/Counter, and it is shared by Timer/Counter1 and Timer/Counter0. Since the prescaler is
not affected by the Timer/Counter’s clock select, the state of the prescaler will have implica-
tions for situations where a prescaled clock is used. One example of prescaling artifacts
occurs when the timer is enabled and clocked by the prescaler (6 > CSn2:0 > 1). The number
of system clock cycles from when the timer is enabled to the first count occurs can be from 1
to N+1 system clock cycles, where N equals the prescaler divisor (8, 64, 256, or 1024).
It is possible to use the prescaler reset for synchronizing the Timer/Counter to program execu-
tion. However, care must be taken if the other Timer/Counter that shares the same prescaler
also uses prescaling. A prescaler reset will affect the prescaler period for all Timer/Counters it
is connected to.
Figure 15-1. Prescaler for Timer/Counter
CLK_I/O
/256, or f
PSRSYNC
Tn
clk
I/O
CLK_I/O
Synchronization
/1024.
CLK_I/O
). Alternatively, one of four taps from the prescaler can be
Clear
CSn0
CSn1
CSn2
ATmega4HVD/8HVD
clk
n
Tn
CLK_I/O
/8, f
CLK_I/O
/64,
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