ATmega165 datasheet(31/336 Pages) ATMEL

Numer części	ATmega165

Szczegółowy opis	8-bit Microcontroller with 16K Bytes In-System Programmable Flash

PDF	336 Pages

Scroll/Zoom	100%

Producent	ATMEL [ATMEL Corporation]

Strona internetowa	http://www.atmel.com

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31 / 336 page

ATmega165/V

2573G–AVR–07/09

Switching Time

When switching between prescaler settings, the System Clock Prescaler ensures that

no glitches occur in the clock system and that no intermediate frequency is higher than

neither the clock frequency corresponding to the previous setting, nor the clock fre-

quency corresponding to the new setting.

The ripple counter that implements the prescaler runs at the frequency of the undivided

clock, which may be faster than the CPU’s clock frequency. Hence, it is not possible to

determine the state of the prescaler – even if it were readable, and the exact time it

takes to switch from one clock division to another cannot be exactly predicted.

From the time the CLKPS values are written, it takes between T1 + T2 and T1 + 2*T2

before the new clock frequency is active. In this interval, 2 active clock edges are pro-

duced. Here, T1 is the previous clock period, and T2 is the period corresponding to the

new prescaler setting.

1101

Reserved

1110

Reserved

1111

Reserved

Table 13. Clock Prescaler Select

CLKPS3

CLKPS2

CLKPS1

CLKPS0

Clock Division Factor

ATmega165 Arkusz danych(PDF) 31 Page - ATMEL Corporation