Near-infrared communication circuit under power failure

Abstract

The utility model relates to a near-infrared communication circuit under power failure. The near-infrared communication circuit comprises a communication circuit and a power supply control circuit, the communication circuit comprises triodes QI2 and QI3, resistors RI1, RI2, RI3, RI4 and RI5, an infrared receiving tube DI2 and an infrared transmitting tube DI1; one end of the resistor RI6 is connected with a driving power supply VCC, and the other end of the resistor RI6 and one end of the resistor RI7 are used for being connected with a control pin InfaredPowerControl of a power supply; the other end of the resistor RI7 is connected with a drain resistor of the MOS tube QI1; the source electrode S of the MOS tube QI1 is connected with a power supply VCC, and the grid electrode D of the MOS tube QI1 outputs voltage VIND; the power supply control circuit comprises resistors RI6 and RI7 and a P-channel MOS (Metal Oxide Semiconductor) tube QI1; the negative electrode of the infrared receiving tube DI2 and the collector electrodes of the triodes QI2 and QI3 are connected to a driving voltage VIND, and the positive electrode of the infrared receiving tube DI2 is connected to the base electrode of the triode QI2 and connected to one end of the resistor RI5; the device is reasonable in design, compact in structure and convenient to use.

Description

Technical Field

[0001] This utility model relates to a near-infrared communication circuit under power outage conditions. Background Technology

[0002] Near-infrared communication generally does not use modulation. To resist interference, the transmitter and receiver need to communicate at a very short distance, almost touching each other. Therefore, external interference is less affecting near-infrared communication, resulting in higher communication speeds. Currently, in near-infrared communication, the general process involves a near-infrared current driving an infrared light-emitting diode (LED), causing the LED to produce alternating bright and dark fluctuations, which in turn allows the infrared receiver to receive the information.

[0003] Most smart meters overseas feature near-infrared (NIIR) communication. Typically, NIIR communication uses a baud rate of 300-9600 bits and operates in a 3.3V system. Because NIIR transmitters have high power during communication, they are generally not used when the power is off. In some areas where power-off data reading is required, logic control is added to the NIIR power supply.

[0004] Most existing near-infrared communication circuits convert AC power to a 3.3V voltage to drive the infrared transmitter and receiver. The MCU then sends a modulated digital signal, which passes through transistors and the transmitter and receiver to complete the information transmission process. When power is off, there is no external AC power input. The microcontroller detects the power failure, and conventional near-infrared circuits cannot directly use near-infrared for communication. Therefore, this invention re-selects the near-infrared circuit and components, using a power-off wake-up mechanism and MOS transistors to control the voltage and other conditions to drive the infrared circuit.

[0005] Currently, commonly used near-infrared communication circuits generally cannot communicate when the power is off. However, in the overseas smart meter market, there is still a significant demand for communication and data reading after the meter is powered off. To enable near-infrared communication circuits to perform communication and data reading after power off, this invention designs a near-infrared circuit that can communicate by being woken up after power off, making some improvements to conventional near-infrared circuits. Utility Model Content

[0006] The technical problem to be solved by this utility model is to provide a near-infrared communication circuit under power outage conditions.

[0007] To solve the above problems, the technical solution adopted by this utility model is as follows:

[0008] A near-infrared communication circuit under power failure conditions includes a communication circuit and a power control circuit.

[0009] The communication circuit includes transistors Qi2 and Qi3, resistors RI1, RI2, RI3, RI4, and RI5, infrared receiver DI2, and infrared transmitter DI1.

[0010] One end of resistor RI6 is connected to the drive power supply VCC, and the other end, along with one end of resistor RI7, is used to connect to the power supply control pin Infrared_Power_Control.

[0011] The other end of resistor RI7 is connected to the drain resistor of MOSFET QI1; the source S of MOSFET QI1 is connected to power supply VCC, and the gate D outputs voltage VIND.

[0012] The power control circuit includes resistors RI6 and RI7, and a P-channel MOSFET QI1;

[0013] The negative terminal of infrared receiver DI2 is connected to the collectors of transistors QI2 and QI3, which are connected to the driving voltage VIND. The positive terminal of infrared receiver DI2 is connected to the base of transistor QI2 and to one end of resistor RI5. The collector of transistor QI2 is connected to one end of resistor RI4 and the near-infrared received signal Infrared RXD. The other ends of resistors RI5 and RI4 are grounded.

[0014] The base of transistor Qi3 is connected to one end of resistor RI1, and the other end of resistor RI1 is connected to the infrared emitter Infrared TXD. The collector of transistor Qi3 is connected to one end of resistor RI2.

[0015] The other end of resistor RI2 is connected to the positive terminal of infrared emitting tube DI1, and the negative terminal of emitting tube DI1 is grounded; resistor RI3 is connected in parallel across the two ends of emitting tube DI1.

[0016] As a further improvement to the above technical solution:

[0017] Resistors RI1, RI2, RI3, RI4, RI5, RI6, and RI7 are surface mount resistors.

[0018] Transistors QI2 and QI3 are NPN type.

[0019] The Infrared_Power_Control pin is derived from the MCU;

[0020] The received signal Infrared RXD comes from the MCU;

[0021] The infrared transmitter Infrared TXD corresponds to the transmit pin Infrared TXD of the MCU;

[0022] Infrared receiver DI2 receives the infrared signal from the corresponding host computer;

[0023] Infrared transmitter DI1 transmits signals to the host computer receiver.

[0024] When in a static state, if the infrared receiver DI2 has no infrared signal or the amount received by the infrared receiver DI2 is lower than the set threshold, the infrared receiver DI2 is in a reverse cutoff state.

[0025] When the base of transistor QI2 is pulled down to a low level by resistor RI5, transistor QI2 is turned on, and the infrared receiver port Infrared RXD is at a high level.

[0026] When the infrared receiver DI2 receives the optical signal from the transmitter of the host computer and converts it into an electrical signal, the infrared receiver DI2 is in the conducting state. When the voltage difference between the base and emitter of the transistor Qi2 is set to a certain value, the transistor Qi2 is in the conducting state.

[0027] The received signal Infrared RXD is pulled down to ground through resistor RI to be in a low-level state for data transmission.

[0028] When the infrared transmitter TXD is in a low-level state, the transistor Qi3 is turned on; the infrared transmitter DI1 is turned off and turns on to generate an infrared signal to be transmitted to the host computer receiver.

[0029] When the infrared transmitter TXD is emitting a high level, transistor QI3 is cut off, and the positive terminal of infrared transmitter DI1 is grounded through resistor RI3.

[0030] Near-infrared communication circuits include wake-up circuits;

[0031] The wake-up circuit includes button KT1, resistor R25, capacitor C19, and wake-up signal DISplay Key;

[0032] The wake-up signal DISplay Key is connected to voltage MVDD through resistor R25, and the wake-up signal DISplay Key is grounded through capacitor C19. Capacitor C19 is connected in parallel to button KT1.

[0033] When powered on, the Infrared_Power_Control pin output is at a low level, the MOSFET QI1 is in the on state, and the VCC flows to the voltage VIND to power the near-infrared system, enabling near-infrared communication.

[0034] When the power is off, the near-infrared power control pin is pulled to a high level through the pull-up resistor RI6, the MOSFET QI1 is turned off, and near-infrared communication stops.

[0035] When the power-down action is performed, button KT1 is turned on, entering the power-down communication mode. At this time, the control pin InfraredPower_Control is in the output low level state, which turns on MOSFET QI1 to provide power and conduct communication.

[0036] This utility model meets the needs of offline communication in some areas. It features a simple circuit, high sensitivity, and strong adaptability and practicality. The design is reasonable, low-cost, sturdy, durable, safe, reliable, easy to operate, time-saving, labor-saving, cost-effective, compact, and convenient to use. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the near-infrared communication circuit of this utility model.

[0038] Figure 2 This is a schematic diagram of the button circuit structure of this utility model.

[0039] Figure 3 This is a schematic diagram of the MCU structure of this utility model.

[0040] Figure 4 This is a schematic diagram of the circuit flow of this utility model. Detailed Implementation

[0041] like Figure 1-4The core of this utility model is to provide a near-infrared communication circuit that can perform data reading in the event of a power outage. The near-infrared communication circuit includes the following components: NPN transistors QI2 and QI3, surface mount resistors RI1, RI2, RI3, RI4, RI5, RI6, and RI7, an infrared receiver DI2, an infrared emitter DI1, and a P-channel MOSFET QI1. Among them: (1) One end of resistor RI6 is connected to the 3.3V driving power supply VCC, and the other end is connected to the power control pin Infrared_Power_Control of one end of resistor RI7. The other end of resistor RI7 is connected to the drain resistor of MOSFET QI1. The source S of MOSFET QI1 is connected to the power supply VCC, and the gate D outputs voltage VIND. The negative terminal of the infrared receiver DI2 is connected to the collectors of PNP transistors QI2 and QI3, which are connected to the driving voltage VIND. The positive terminal of the receiver is connected to the base of QI2, which is connected to one end of resistor RI5. The collector of transistor QI2 is connected to one end of resistor RI4 and the near-infrared received signal Infrared RXD. The other ends of resistors RI5 and RI4 are grounded. (2) The base of transistor QI3 is connected to one end of resistor RI1. The other end of resistor RI1 is connected to the infrared transmitter Infrared TXD. The collector of transistor QI3 is connected to one end of resistor RI2. The other end of RI2 is connected to the positive terminal of infrared transmitter DI1. The negative terminal of transmitter DI1 is grounded. Resistor RI3 is connected in parallel across transmitter DI1. This constitutes the communication circuit and power control circuit of this utility model.

[0042] The following is combined with Figure 1The principle of near-infrared communication circuit is analyzed as follows: (1) In the static state, when the infrared receiver tube has no infrared signal (or only a very weak infrared signal), the infrared receiver tube is in the reverse cutoff state. The base of transistor QI2 is pulled down to the low level by resistor RI5. At this time, the transistor is turned on, and the infrared receiver port Infrared RXD is at the high level. When the host computer issues a command, the infrared tube of the host computer emits an infrared signal. The infrared receiver tube DI2 receives the light signal of the transmitter tube of the host computer and converts it into an electrical signal. At this time, the infrared receiver tube DI2 is no longer reverse cutoff and starts to conduct. The base-emitter voltage difference of transistor QI2 is greater than 0.7V, the transistor is turned on, and Infrared RXD is pulled down to ground by resistor RI to become low level, thus completing the data transmission. (2) After the information is processed by the MCU, the MCU's transmit pin, Infrared TXD, sends a square wave signal consisting of high and low levels at the set baud rate. This square wave signal controls the transistor QI3 to switch continuously. When TXD is at a low level, QI3 is turned on, ending the infrared transmitter's cutoff state. The infrared transmitter then generates an infrared signal that varies with the current and is transmitted to the host computer's receiver. When TXD is at a high level, transistor QI3 is cut off, and the positive terminal of the transmitter is grounded by resistor RI3. There is no voltage drop across the infrared transmitter, and no current flows (or a very small current signal), thus no infrared signal is generated. Communication with the host computer can be achieved through the coordinated use of the receiving and transmitting circuits.

[0043] When powered on, the Infrared_Power_Control pin outputs a low level, MOSFET Qi1 conducts, and VCC flows to voltage VIND to power the near-infrared system, enabling near-infrared communication. When powered off, the near-infrared power control pin is pulled high by pull-up resistor RI6, the MOSFET does not conduct, and near-infrared communication is impossible. To perform a power-off operation, wake-up is required by pressing and holding the button for 10 seconds to enter power-off communication mode. In this mode, Infrared_Control outputs a low level, turning on the MOSFET to provide power and initiate communication.

[0044] In practical implementation, TXD is connected in series with a 1KΩ current-limiting resistor to the base of QI3. In the default state, the MCU outputs a high level. When the MCU sends a signal, the pin is set low, the transistor conducts, and the infrared emitter operates. Adjusting the resistance of RI2 controls the power of the infrared emitter. RXD is connected in series with a 10KΩ protection resistor to the output pin of the infrared receiver. Simultaneously, a 36KΩ pull-down resistor connected to GND ensures that the base of QI2 is normally low, QI2 is in the conducting state, and RXD is high. When the receiver receives a signal, the base of QI2 is high, RXD is pulled low, and communication is achieved. Resistor RI5 has a resistance of 36KΩ, resistors RI4 and RI1 are 10KΩ, RI6 is 2MΩ, RI7 is 20KΩ, and RI3 is 100Ω. Resistors RI4 and RI5 act as pull-down resistors to ensure that transistor QI2 is in the off state when communication is not in progress, allowing RXD to be pulled low. Resistor RI2 is a current-limiting resistor; adjusting the value of resistor RI2 controls the current flowing through the emitter, thus controlling the light intensity. Resistor RI6 is a pull-up resistor, used to pull the Infrared_Power_Control pin high to prevent the MOS from accidentally turning on.

[0045] This utility model is described in detail for the purpose of making the disclosure clearer, and the prior art will not be listed one by one.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. It is obvious to those skilled in the art that multiple technical solutions of this utility model can be combined. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model. All technical contents not described in detail in this utility model are publicly known technologies.

Claims

1. A near-infrared communication circuit under power outage conditions, characterized in that: This includes communication circuits and power control circuits; The communication circuit includes transistors Qi2 and Qi3, resistors RI1, RI2, RI3, RI4, and RI5, infrared receiver DI2, and infrared transmitter DI1. One end of resistor RI6 is connected to the drive power supply VCC, and the other end, along with one end of resistor RI7, is used to connect to the power supply control pin Infrared_Power_Control. The other end of resistor RI7 is connected to the drain resistor of MOSFET QI1; the source S of MOSFET QI1 is connected to power supply VCC, and the gate D outputs voltage VIND. The power control circuit includes resistors RI6 and RI7, and a P-channel MOSFET QI1; The negative terminal of infrared receiver DI2 is connected to the collectors of transistors QI2 and QI3, which are connected to the driving voltage VIND. The positive terminal of infrared receiver DI2 is connected to the base of transistor QI2 and to one end of resistor RI5. The collector of transistor QI2 is connected to one end of resistor RI4 and the near-infrared received signal Infrared RXD. The other ends of resistors RI5 and RI4 are grounded. The base of transistor Qi3 is connected to one end of resistor RI1, and the other end of resistor RI1 is connected to the infrared emitter InfraredTXD. The collector of transistor Qi3 is connected to one end of resistor RI2. The other end of resistor RI2 is connected to the positive terminal of infrared emitting tube DI1, and the negative terminal of emitting tube DI1 is grounded; resistor RI3 is connected in parallel across the two ends of emitting tube DI1.

2. The near-infrared communication circuit under power outage conditions according to claim 1, characterized in that: Resistors RI1, RI2, RI3, RI4, RI5, RI6, and RI7 are surface mount resistors.

3. The near-infrared communication circuit under power outage conditions according to claim 1, characterized in that: Transistors QI2 and QI3 are NPN type.

4. The near-infrared communication circuit under power outage conditions according to claim 1, characterized in that: The control signal InfraredPower_Control comes from the MCU; the receiving signal pin Infrared RXD is connected to the MCU; the transmitting signal pin InfraredTXD is connected to the MCU; the infrared receiver DI2 corresponds to the infrared transmitter of the host computer; the infrared transmitter DI1 corresponds to the infrared receiver of the host computer.

5. The near-infrared communication circuit under power outage conditions according to claim 1, characterized in that: When in a static state, if the infrared receiver DI2 has no infrared signal or the amount received by the infrared receiver DI2 is lower than the set threshold, the infrared receiver DI2 is in a reverse cutoff state. When the base of transistor QI2 is pulled down to a low level by resistor RI5, transistor QI2 is turned on, and the infrared receiver port Infrared RXD is at a high level.

6. The near-infrared communication circuit under power outage conditions according to claim 1, characterized in that: When the infrared receiver DI2 receives the optical signal from the host computer's transmitter and converts it into an electrical signal, the infrared receiver DI2 is in the on state. When the voltage difference between the base and emitter of the transistor Qi2 is set to a certain value, the transistor Qi2 is in the off state. The receiver pin Infrared RXD is pulled down to ground through resistor RI4 and is in a low level state. When the infrared receiver DI2 does not receive the optical signal from the host computer's transmitter, the infrared receiver DI2 is in the off state, the transistor Qi2 is on, and the receiver pin Infrared RXD is pulled up to a high level by VIND, thereby enabling data transmission.

7. The near-infrared communication circuit under power outage conditions according to claim 1, characterized in that: When the infrared signal transmitting pin Infrared TXD is in a low level state, transistor Qi3 is turned on; infrared emitting diode DI1 is no longer in the cut-off state, and infrared emitting diode DI1 is turned on to generate an infrared signal for transmission to the host computer receiving tube. When the infrared emitting pin Infrared TXD is at a high level, transistor QI3 is cut off, and the positive terminal of infrared emitting diode DI1 is grounded through resistor RI3.

8. The near-infrared communication circuit under power outage conditions according to claim 1, characterized in that: Near-infrared communication circuits include wake-up circuits; The wake-up circuit includes button KT1, resistor R25, capacitor C19, and wake-up signal DISplay Key; The wake-up signal Display Key is connected to voltage MVDD through resistor R25, and the wake-up signal DISplay Key is grounded through capacitor C19. Capacitor C19 is connected in parallel to button KT1.

9. The near-infrared communication circuit under power outage conditions according to claim 8, characterized in that: When powered on, the Infrared_Power_Control pin output is at a low level, the MOSFET QI1 is in the on state, and the VCC flows to the voltage VIND to power the near-infrared system, enabling near-infrared communication. When the power is off, the near-infrared power control pin is pulled to a high level through the pull-up resistor RI6, the MOSFET QI1 is turned off, and near-infrared communication stops. When the power-down action is performed, button KT1 is turned on, entering the power-down communication mode. At this time, the control pin Infrared Power_Control is in the output low level state, which turns on MOSFET QI1 to provide power and conduct communication.

Images