AT89C51IC2-SLSCM datasheet(22/146 Pages) ATMEL

Part #	AT89C51IC2-SLSCM

Description	8-bit Flash Microcontroller with 2-wire Interface

PDF	146 Pages

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Manufacturer	ATMEL [ATMEL Corporation]

Direct Link	http://www.atmel.com

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22 / 146 page

AT89C51IC2

4301A–8051–01/04

Figure 6. Mode Switching Waveforms

The X2 bit in the CKCON0 register (see Table 19) allow to switch from 12 clock periods

per instruction to 6 clock periods and vice versa. At reset, the speed is setting according

to X2 bit of Hardware Security Byte (HSB). By default, Standard mode is actived. Setting

the X2 bit activates the X2 feature (X2 mode).

The T0X2, T1X2, T2X2, UartX2, PcaX2, WdX2 and I2CX2 bits in the CKCON0 register

(See Table 19.) and SPIX2 bit in the CKCON1 register (see Table 20) allow to switch

from standard peripheral speed (12 clock periods per peripheral clock cycle) to fast

peripheral speed (6 clock periods per peripheral clock cycle). These bits are active only

in X2 mode.

More information about the X2 mode can be found in the application note "How to take

advantage of the X2 features in TS80C51 microcontroller?"

XTALA1:2

XTALA1

CPU clock

X2 bit

X2 Mode

STD Mode

OSCA

AT89C51IC2-SLSCM Datasheet(PDF) 22 Page - ATMEL Corporation