The maximum operating frequency of STC12IE90HV is 24 MHz, but it can be overclocked up to 30 MHz with some limitations.
The internal oscillator of STC12IE90HV can be configured using the OSCXCF and OSCCAL registers. The OSCXCF register sets the oscillator frequency range, and the OSCCAL register fine-tunes the oscillator frequency.
The RSTDISBL bit in the STC12IE90HV disables the reset pin (RST) and allows it to be used as a general-purpose I/O pin. This is useful when the reset function is not needed or when the pin is needed for other purposes.
The watchdog timer (WDT) in STC12IE90HV can be enabled by setting the WDTE bit in the WDTCSR register. The WDT timeout period can be set using the WDP0-WDP3 bits in the WDTCSR register. The WDT can be reset using the WDR instruction or by writing to the WDTCSR register.
The main difference between the STC12IE90HV and STC12C5A60S2 is the operating voltage range. The STC12IE90HV operates from 2.2V to 5.5V, while the STC12C5A60S2 operates from 4.5V to 5.5V. The STC12IE90HV also has a higher maximum operating frequency (24 MHz vs 20 MHz).
STC12IE90HV datasheet
by STMicroelectronics
