at89c51ac3-s3sim ATMEL Corporation, at89c51ac3-s3sim Datasheet - Page 17

• Manufacturer Part Number: at89c51ac3-s3sim
• Description: At89c51ac3 Enhanced 8-bit Microcontroller With 64kb Flash Memory
• Manufacturer: ATMEL Corporation

Figure 6. Mode Switching Waveforms
Note:
4383D–8051–02/08
In order to prevent any incorrect operation while operating in the X2 mode, users must be aware that all peripherals using the
clock frequency as a time reference (UART, timers...) will have their time reference divided by two. For example a free running
timer generating an interrupt every 20 ms will then generate an interrupt every 10 ms. A UART with a 4800 baud rate will have
a 9600 baud rate.
XTAL1
XTAL1/2
X2 bit
CPU clock
STD Mode
X2 Mode
STD Mode
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