Microcomputer with an integrated RC oscillator having programmable frequencies

摘要

In a monolithically integrated microcomputer clocked by means of a processor clock and having a central processing unit and having at least one function unit operating asynchronously to the processor clock and controlled by a clock generator which can be synchronised by external signals, the clock generator being implemented in the form of an RC oscillator, it is proposed that the frequency-determining resistance and the frequency-determining capacitance of this RC oscillator are monolithically integrated, that the frequency-determining capacitance is implemented by a multiplicity of switchable capacitances which can be connected together to form a total capacitance of variable magnitude and that the frequency of the clock generator is adjusted by corresponding registers, determining the switching state of the switchable capacitances, being set by the central processing unit. It is proposed that the processor clock is provided as reference for the frequency setting of the clock generator. IMAGE