RU188979U1 - Transceiver with galvanic isolation - Google Patents

Abstract

The technical solution relates to the field of electronics, in particular, to devices for receiving and transmitting information between embedded processors, and can be used for receiving and transmitting information through RS-485, RS-422 interfaces with galvanic decoupling, in automatic control systems and systems for collecting and processing information. The essence of the proposed technical solution lies in the fact that the transceiver device with galvanic decoupling contains a microcontroller, drivers for digital data transmission interfaces, linguistic transformer and made with the ability to transfer data through a decoupling transformer through a hardware module UART, due to software NRZ coding. 2 Il.

Description

The technical solution relates to the field of electronics, in particular, to devices for receiving and transmitting information between embedded processors, and can be used for receiving and transmitting information through RS-485, RS-422 interfaces with galvanic decoupling, in automatic control systems and systems for collecting and processing information.

The use of transformer-based technical solutions for the transmission of data and / or energy through galvanic isolation is known in the art. These technical solutions are used in industrial equipment, medical equipment, robotics, lighting systems and other devices that require the protection of high-voltage sensitive elements.

The main direction in the development of transceiver devices is to reduce costs, reduce size, use in the construction of standard components. One of the options to achieve these improvements is the implementation of galvanic isolation based on transformers that perform data and energy transmission, excluding additional electrical isolation of power supplies.

From the Russian patent for invention No. 2254671, a method of transmitting control signals with galvanic isolation and a device for its implementation is known. In the described invention, the device includes a transformer, five resistors, three diodes, a level converter, a source of rectangular pulses and a transistor.

The disadvantages of the technical solution include a multi-element scheme of the device, which leads to an increase in its size and cost.

Also known is a transceiver circuit with a transformer galvanic decoupling described in US patent 7683654 B2 of 04.30.2003 "Signal isolators circuit micro-transformers".

In the described device, a pulse transformer is used as galvanic isolation, which is connected between the pulse shaper and the transmitter amplifier, placed inside the microcircuit and has no direct connection with external circuits. Pulse transformer divides the transceiver circuit into two parts. One of them has a galvanic connection with the equipment, which includes a transceiver, which is powered by a common power source with the equipment. The other part does not have a galvanic connection with the main equipment and requires an additional power source galvanically isolated from the main equipment.

As the closest analogue, a technical decision has been made that is protected by the RF patent for invention No. 2511429 dated 19.17.2012 from which the transceiver of the serial interface with the element of galvanic isolation is known. The device described in the patent contains a galvanic decoupling element, an input information encoder connected in series, a pulse width driver, a transmitter terminal amplifier, and a receiver input amplifier connected in series and a decoder. A galvanic isolation element is connected between the terminal amplifier of the transmitter and the communication line, and the input of the amplifier of the receiver is connected to the output of the terminal amplifier of the transmitter. The input signals to the galvanic decoupling element are encoded by two bipolar pulses corresponding to the front and the decay of the input signal.

The disadvantages of the described technical solution include the use in the design of a pulse transformer, which can lead to inaccuracies in signal transmission when it is saturated, the use of additional elements of the formation and amplification of pulses complicates the design of the device and may lead to an increase in cost and size.

The technical task, the solution of which is the claimed technical solution is the creation of a device for receiving / transmitting data via RS-485, RS-422 interfaces of reduced dimensions using standard components, as well as ensuring noise immunity and reliability in operation.

The technical result achieved from the implementation of the proposed utility model is to reduce the size of the device, reducing cost, improving the accuracy of signal transmission.

The essence of the proposed technical solution is that the transceiver device with galvanic decoupling contains a microcontroller, digital data transfer interface drivers, an isolation transformer and is configured to transmit / receive data via an isolation transformer via a Universal Asynchronous Receiver-Transmitter UART hardware module (non return to zero) encoding / decoding the input signal.

According to one of the possible options for implementing a technical solution, the microcontroller contains a Compare Output module, combined with a receive / transmit input switching control timer in RS-485, RS-422 digital data interface drivers.

The essence of the proposed technical solution is explained, but not limited to the graphic materials:

figure 1 - block diagram of a transceiver device with galvanic decoupling (option 1);

figure 2 - block diagram of a transceiver device with galvanic decoupling (option 2).

According to one possible implementation variant of the proposed technical solution, the device contains at least one microcontroller 1 (FIG. 1.2), drivers 2 interfaces of digital data transmission RS-485, RS-422, and at least one isolation transformer 3 with terminal load resistors 4.

In one of the possible options for implementing a technical solution, the device is implemented on the basis of a standard microcontroller, which contains: a data block DATA (5, 6), a software NRZ encoding / decoding block (7, 8), a converter of the transmitted / received data into a serial form in the form of hardware UART module 9,10. Also, the specified micron controller (MC) contains a comparison module 11 Output Compare, combined with a timer 12 controlling the input of the switching input / transmission in the drivers 2 of the RS-485, RS-422 digital data transmission interfaces by means of the Direction control signal. Using a timer with hardware switching of terminals MK by controlling the time of signal passing through the UART 9,10 modules to the windings of an isolation transformer allows you to avoid oversaturation of the transformer, thereby improving the signal quality and reliability of the transceiver.

The comparison module works in conjunction with a timer. Predominantly, the operation of the module is based on comparing the value of the timer register with the value of one or two registers of the comparison module (depending on the mode of operation of the module). The state on the output pin of this module changes when the timer value matches the value in the compare register.

The comparison module generates either a single pulse or a sequence of pulses at the output, changing the output state of the MC in accordance with the mode of operation:

- interruption of UART data transmission;

- filling the UART transmitter buffer;

- cancellation of interruption;

- start the timer at the time equal to the length of the data packet + 1 bit;

- UART data transmission.

In another possible implementation of the device, switching can be implemented by means of an RTS signal.

To build an interface based on the considered transceiver with an element of galvanic isolation, a differential pair of 13 is used. Since differential signals are more resistant to electromagnetic interference than single conductors, this connection method improves the quality of the transmitted signal.

The operation of the proposed technical solution according to the described embodiment can be described as follows.

Signals with DATA data coming into the microcontroller are fed to the NRZ encoding / decoding software block (7, 8) to convert the information into digital form with a subsequent signal transfer to the hardware UART module which can be implemented either on the basis of the MC, or as a separate microcircuit, providing communication with other digital devices, in particular with drivers of 2 interfaces of digital data transmission RS-485, RS-422, connected to the windings of a transformer, providing galvanic isolation of signals and power supply I Un different polarity to the MC. In an embodiment of the device (FIG. 2), an additional transformer 14 is included in the device circuit, which allows using the driver of the digital data interface RS-422.

In each of the above options for the implementation of the device, through a comparison module 11 Output Compare, combined with timer 12, provide control of the signal transit time (data packet) through the UART module by controlling the switching of MC pins excluding the saturation of the isolation transformer.

Implementation of the proposed technical solution contributes to the achievement of the technical result, providing a reduction in the size of the device, simplifying the scheme and method of its operation, which leads to a decrease in cost, as well as improving the accuracy of signal transmission.

Claims (1)

Transceiver device with galvanic decoupling, containing a microcontroller (MC), digital data transmission interface drivers and an isolation transformer, characterized in that it is capable of transmitting / receiving data through an isolation transformer connected to the microcontroller by means of the UART hardware module combined with the MC and associated module of the NRZ software for encoding / decoding the input signal; the UART module is also associated with the drivers of digital data transmission interfaces associated with the windings of t the transformer, in this case, the specified MK contains a comparison module, configured to change the state of the MK pins, combined with a receive / transmit control switch input timer in the drivers of digital data transmission interfaces.

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