AT85C5122D-RDRUM datasheet(44/208 Pages) ATMEL

部件名	AT85C5122D-RDRUM

功能描述	C51 Microcontroller with USB and Smart Card Reader Interfaces

PDF	208 Pages

Scroll/Zoom	100%

制造商	ATMEL [ATMEL Corporation]

网页	http://www.atmel.com

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44 / 208 page

AT83R5122, AT8xC5122/23

4202F–SCR–07/2008

Figure 20.

X1 mode

When the X1 mode is selected, the CPU and Peripherals work at 8Mhz / X1

Figure 21.

X2 mode

When the X2 mode is selected, the CPU works at 8 MHz / X2. The Peripherals can work

at 8 MHz / X2 or 8 MHz / X1.

When the PR1 prescaler is different from 1/2, the usual X1 mode can not be defined. In

this case, it is necessary to define a X1 or X2 equivalent mode from equivalent clock

circuits.

Example : PR1=1/8, X2=0.

In this configuration, the CPU works at 1 MHz. This frequency could also be obtained by

an equivalent clock circuit where the on-chip oscillator would run at 2 MHz in X1 mode

or at 1 MHz in X2 mode. So we can say that the CPU works at 2 MHz / X1 or 1MHz / X2.

As the X2 bit is cleared in CKCON0 register, we have FCK_IDLE = FCK_PERIPH.

8 MHz

1/2

PR1 prescaler

CPU frequency

4 MHz

Peripheral frequency

Crystal

8 MHz

CPU frequency (X2 Mode)

8 MHz

Peripheral frequency (X2 mode)

4 MHz

1/2

Peripheral frequency (X1 mode)

Internal Prescaler

Crystal

AT85C5122D-RDRUM 数据表(PDF) 44 Page - ATMEL Corporation