Figure 4. Mode Switching Waveforms(1)
XTAL1
XTAL2
X2 bit
CPU
clock
STD
X2
STD
Mode
Mode
Mode
Note:
1. 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 2. For example, a free run-
ning 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.
16
AT89C5115
4128F–8051–05/06