Method for recalibrating base line PIC single chip microcomputer inner oscillator

Abstract

The invention relates to the field of single chip microcomputers, in particular to a method for recalibrating oscillating frequency of a base line PIC single chip microcomputer inner oscillator of the Microchip company. The method has the advantages that only one software program of a single chip microcomputer which needs recalibrating needs to be designed, the serial asynchronous communication principle is used, the single chip microcomputer is used as a sending end, asynchronous clock signals of a receiving end are used as a reference source, the single chip microcomputer sends specific data and a current calibrating value under different oscillating frequencies, and receiving is carried out through the receiving end. When the receiving end receives correct sent data, a clock sent by the sending end and a received clock of the receiving end are consistent, the frequency of the current single chip microcomputer inner oscillator is determined hereby, and accordingly the calibrating value is obtained. According to the calibrating value, the inner oscillator can work within + / - 0.5% of the nominal oscillating frequency theoretically.

Description

technical field [0001] The invention relates to the field of single-chip microcomputers, and mainly relates to the recalibration of the oscillation frequency of the internal oscillator of the baseline PIC single-chip microcomputer of Microchip Company with an internal oscillator. technical background [0002] Except for the three models of PIC16F54 / 57 / 59, Microchip's baseline PIC microcontrollers have internal oscillators, and the oscillation frequency of the internal oscillators is generally calibrated at ±1% at the factory. These single-chip microcomputers can add 1 to 2 I / O port lines when using the internal oscillator, which brings greater convenience to users. The baseline PIC microcontroller with an internal oscillator is programmed with an instruction MOVLW XX in the last unit of the program memory when it leaves the factory, where XX is the calibration value, and the address of this unit is stored in the reset vector. When reset, the MOVLW XX instruction is automati...

AI Technical Summary

Problems solved by technology

This method first needs to build an oscillator or prepare a standard signal source, and secondly, it needs to design a display circuit to display the calibration value, which increases the difficulty of hardware and software design.

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