A UART/I2C bus programmable pull-up voltage control circuit

Abstract

The invention discloses a UART / I2C bus programmable pull-up voltage control circuit, and the circuit comprises a single-chip microcomputer which is used for outputting a PWM square wave signal with aspecified duty ratio; a low-pass filter used for processing the input PWM square wave signal into a stepless adjustable simulation voltage; and a voltage follower used for receiving the simulation voltage signal, so that the output end of the voltage follower outputs a stable voltage signal. According to the UART / I2C bus programmable pull-up voltage control circuit provided by the invention, the pull-up voltage in different ranges is output by adjusting the PWM square wave duty ratio, so that the circuit is simplified, the occupation of an I / O bus is reduced, the use of electrical components is reduced, and the operation cost is saved.

Description

technical field [0001] The invention relates to the technical field of control circuits, in particular to a UART / I2C bus programmable pull-up voltage control circuit. Background technique [0002] UART (Universal Asynchronous Receiver Transmitter) and I2C (Inter-Integrated Circuit) buses are currently widely used in electronic products, and have the characteristics of low cost and high benefit. However, due to different application occasions, the pull-up voltage range they use is 1.8V ~ 12V. The current way to deal with it is to design a dedicated bus circuit for various needs, use a fixed pull-up voltage, and cannot flexibly change the pull-up voltage. It is necessary to make hardware changes, or use I / O lines to select different pull-up voltage. The disadvantage of the above method is that it takes up I / O line resources, and all possible pull-up voltages must be pre-fabricated in the circuit. For example, if four kinds of pull-up voltages need to be input, four pull-up v...

AI Technical Summary

Problems solved by technology

The current solution is to design a dedicated bus circuit for various needs, use a fixed pull-up voltage, and cannot flexibly change the pull-up voltage. It is necessary to make hardware changes, or use I / O lines to select different pull-up voltage

The disadvantage of the above method is that it takes up I / O line resources, and all possible pull-up voltages must be pre-fabricated in the circuit. For example, if four kinds of pull-up voltages need to be input, four pull-up voltages must be prepared. Voltage source, occupying at least 2 I / O lines for voltage selection

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