C51MCUS

A high on the RST pin for several machine cycles while the oscillator C51MCUS is running, resets the C51MCUS. An internal resistor to VSS permits a power-on reset using only an external capacitor to VCC. While this pin is forced high, the MCU Core C51MCUS is halted from executing code, the peripherals are stopped and the I/Os are tri-stated.

The RST pin C51MCUS is an output when the Hardware Watchdog Timer times out and forces a system reset. When Watchdog Timer overflows, it drives an output RST HIGH pulse at the RST pin. When the watchdog is used, a resistor Rrst mounted in serial with the external capacitor Crst or reset circuit is necessary to allow the Hardware Watchdog to drive the RST pin.