Method of serially processing binary characters asynchronously received

Abstract

A method of processing binary characters received by an electrical energy meter includes the step of generating a clock signal internal to the meter so that asynchronously received serial data can be processed, even though a synchronization clock signal does not accompany the serial data. The method includes the steps of detecting receipt of a first of a string of binary input characters at a serial input/output port of the meter, and then sampling the detected first character by generating a respective first clock signal which is phase-synchronized with a least significant bit of the first character. These steps are then repeated in sequence for each subsequently received character in the string. The sampled characters can be temporarily stored in meter hardware such as a register and written to memory such as programmable read-only or random-access memory. Phase-synchronization between the sampling clock signals and each of the respective characters is achieved even though the data rate of the binary string (e.g., 9600 bits/sec) is unequal to an integer fraction of the frequency of the main crystal oscillator of the meter (e.g., 4.19 MHz), which controls meter operations.