CN113518277B - Bidirectional communication circuit of real wireless Bluetooth headset charging system - Google Patents
Bidirectional communication circuit of real wireless Bluetooth headset charging system Download PDFInfo
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- CN113518277B CN113518277B CN202110455080.XA CN202110455080A CN113518277B CN 113518277 B CN113518277 B CN 113518277B CN 202110455080 A CN202110455080 A CN 202110455080A CN 113518277 B CN113518277 B CN 113518277B
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- 230000007175 bidirectional communication Effects 0.000 title description 7
- 230000006854 communication Effects 0.000 claims abstract description 54
- 238000004891 communication Methods 0.000 claims abstract description 54
- 238000013461 design Methods 0.000 abstract description 7
- 230000008901 benefit Effects 0.000 abstract description 5
- 238000005070 sampling Methods 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 16
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- 238000010586 diagram Methods 0.000 description 3
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- 230000009286 beneficial effect Effects 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/10—Earpieces; Attachments therefor ; Earphones; Monophonic headphones
- H04R1/1025—Accumulators or arrangements for charging
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/10—Earpieces; Attachments therefor ; Earphones; Monophonic headphones
- H04R1/1041—Mechanical or electronic switches, or control elements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/80—Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
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- Engineering & Computer Science (AREA)
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- Acoustics & Sound (AREA)
- Computer Networks & Wireless Communication (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention relates to a two-way communication circuit of a real wireless Bluetooth headset charging system, which comprises a first communication circuit positioned in a Bluetooth headset charging box and a second communication circuit positioned in the Bluetooth headset; the first communication circuit is connected with the second communication circuit through the first charging contact and the third charging contact, the first communication circuit comprises a first switch tube, a second switch tube, a resistor R10 and a resistor R7, the second communication circuit comprises a third switch tube, a fourth switch tube and a resistor R8, the first charging contact and the third charging contact are multiplexed by the second communication circuit, single-wire two-way communication between the charging box and the Bluetooth headset is realized, an additional communication circuit is not needed, the design cost of the circuit is reduced, the economic benefit is better, the charging box or the Bluetooth headset can receive signals sent by the charging box or the Bluetooth headset when the charging box or the Bluetooth headset sends signals by the charging box or the Bluetooth headset, and the charging box or the Bluetooth headset is convenient to know the conditions of the signals sent by the charging box or the Bluetooth headset.
Description
Technical Field
The invention relates to the technical field of a real wireless Bluetooth headset charging system, in particular to a two-way communication circuit of the real wireless Bluetooth headset charging system.
Background
In recent years, TWS bluetooth headsets have been on the rise, consisting of two headsets plus a charging box. In order to consider portability, the whole product appearance is smaller, the duration requirement is longer and longer, and even some TWS Bluetooth headsets use the duration as a selling point, so that better market acceptance and acceptance are obtained.
The existing Bluetooth headset and the charging box are generally in one-way communication. In addition, these bluetooth headsets currently boost 3.7 v in the charging box to 5 v with DC/DC, then send to the headset, and charge the battery of the headset with the voltage required for converting 5 v into the battery (typically 3.0 v to 4.2 v) through a voltage-reducing circuit at the headset end. In the process, the DC/DC is in a switch mode, the efficiency can be generally higher than 95%, and the charging circuit in the earphone is in a linear working mode due to the problem of the synchronization of the earphone and the switch of the charging box (the power cannot be normally transmitted due to the fact that the switch is not synchronized), so that the average efficiency is about 65%. During this step-up and step-down conversion, the total power loss is more than 35%.
However, the electric energy stored in the battery of the charging box is limited, but more than 1/3 of the energy is lost in practical use, and the energy-saving requirement is not met. In addition, the endurance time is longer in a limited space, and the improvement of the charging conversion efficiency of the charging box to the earphone is a primary problem which needs to be solved. The charging circuit is not available, and a circuit for communicating with the charging box through the earphone is needed to solve the problem of information delivery between the earphone and the charging box, so that a new scheme is needed to solve the pain point.
Accordingly, in the present application, the applicant has studied a two-way communication circuit of a real wireless bluetooth headset charging system to solve the above-mentioned problems.
Disclosure of Invention
Aiming at the defects of the prior art, the invention mainly aims to provide a bidirectional communication circuit of a real wireless Bluetooth headset charging system, which multiplexes a first charging contact and a third charging contact, realizes single-wire bidirectional communication between a charging box and a Bluetooth headset, does not need an extra communication line, reduces the design cost of the circuit, has better economic benefit, and the charging box or the Bluetooth headset can receive signals sent by the charging box or the Bluetooth headset when sending signals, thereby being convenient for knowing the conditions of the signals sent by the charging box or the Bluetooth headset.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a bidirectional communication circuit of a real wireless Bluetooth headset charging system comprises a first communication circuit positioned in a Bluetooth headset charging box and a second communication circuit positioned in the Bluetooth headset;
the first communication circuit is connected with the second communication circuit through the first charging contact and the third charging contact, the first communication circuit comprises a first switching tube, a second switching tube, a resistor R10 and a resistor R7, the first switching tube is provided with a first switching tube connecting end, a second switching tube connecting end and a first switching tube control end for connecting with a UART_TX pin of a main control chip of the charging box, and the second switching tube is provided with a third switching tube connecting end, a fourth switching tube connecting end for connecting with a UART_RX pin of the main control chip of the charging box and a second switching tube control end for connecting with the first charging contact of the charging box;
the first switch tube connecting end is connected with the third switch tube connecting end and is grounded, the second switch tube connecting end is connected with the second switch tube control end, the resistor R7 is provided with a first resistor connecting end and a second resistor connecting end for connecting a power supply VCC, the first resistor connecting end is connected with the fourth switch tube connecting end, and the second resistor connecting end is connected with the second switch tube control end through a resistor R10;
the second communication circuit comprises a third switching tube, a fourth switching tube and a resistor R8;
the third switching tube is provided with a fifth switching tube connecting end, a sixth switching tube connecting end for connecting with a UART_RX1 pin of the Bluetooth headset main control chip and a third switching tube control end for connecting with a third charging contact of the Bluetooth headset, and the fourth switching tube connecting end Guan Juyou is provided with a seventh switching tube connecting end, an eighth switching tube connecting end and a fourth switching tube control end for connecting with a UART_TX1 pin of the Bluetooth headset main control chip;
the eighth switching tube connecting end is connected with the third switching tube control end, the fifth switching tube connecting end is connected with the seventh switching tube connecting end and is grounded, the resistor R8 is provided with a third resistor connecting end and a fourth resistor connecting end for connecting a power supply VCC, and the third resistor connecting end is connected with the sixth switching tube connecting end;
the first switching tube is an NMOS tube Q2 or an NPN triode Q2, and the second switching tube is an NMOS tube Q4 or an NPN triode Q4.
As a preferable scheme, the third switching tube is an NMOS tube Q8 or an NPN triode Q8, and the fourth switching tube is an NMOS tube Q9 or an NPN triode Q9;
the grid electrode of the NMOS tube Q8 is a third switching tube control end, the source electrode of the NMOS tube Q8 is a fifth switching tube connecting end, and the drain electrode of the NMOS tube Q8 is a sixth switching tube connecting end;
the base electrode of the NPN triode Q8 is a third switching tube control end, the emitter electrode of the NPN triode Q8 is a fifth switching tube connecting end, and the collector electrode of the NPN triode Q8 is a sixth switching tube connecting end;
the grid electrode of the NMOS tube Q9 is a fourth switching tube control end, the source electrode of the NMOS tube Q9 is a seventh switching tube connecting end, and the drain electrode of the NMOS tube Q9 is an eighth switching tube connecting end;
the base electrode of the NPN triode Q9 is a fourth switching tube control end, the emitter electrode of the NPN triode Q9 is a seventh switching tube connecting end, and the collector electrode of the NPN triode Q9 is an eighth switching tube connecting end.
Compared with the prior art, the invention has obvious advantages and beneficial effects, in particular: the first communication circuit is connected with the second communication circuit through the first charging contact and the third charging contact, the first charging contact and the third charging contact are multiplexed, single-wire bidirectional communication between the charging box and the Bluetooth headset is realized, an additional communication circuit is not needed, the circuit design cost is reduced, better economic benefits are achieved, and the charging box or the Bluetooth headset can receive signals sent by the charging box or the Bluetooth headset when the charging box or the Bluetooth headset sends signals, so that the situation of the signals sent by the charging box or the Bluetooth headset can be known conveniently;
and the whole circuit structure is ingenious and reasonable in design, and each circuit is stable in performance, safe and reliable.
In order to more clearly illustrate the structural features and efficacy of the present invention, a detailed description thereof will be given below with reference to the accompanying drawings and examples.
Drawings
FIG. 1 is a general control block diagram of an embodiment of the present invention;
FIG. 2 is a control block diagram of a real wireless Bluetooth headset charging system according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of a real wireless bluetooth headset charging system according to an embodiment of the invention.
Reference numerals illustrate:
10. bluetooth headset charging box circuit
11. First battery
121. Current sampling circuit 122 and voltage sampling circuit
13. First charging switch unit 14, first port
15. Second port 16, first communication circuit
161. First switch tube 162, second switch tube
17. Charging interface
20. Bluetooth earphone circuit
21. Second battery 22, second charging switch unit
23. Third port 24, fourth port
25. Second communication circuit 251, third switch tube
252. And a fourth switching tube.
Detailed Description
The invention is further described below with reference to the drawings and detailed description.
As shown in fig. 1 to 3, a two-way communication circuit of a real wireless bluetooth headset charging system is mainly applied to a real wireless bluetooth headset, and comprises a first communication circuit 16 in a bluetooth headset charging box and a second communication circuit 25 in the bluetooth headset;
the first communication circuit 16 includes a first switch tube 161, a second switch tube 162, a resistor R10 and a resistor R7, where the first switch tube 161 has a first switch tube connection end, a second switch tube connection end, and a first switch tube control end for connecting with a uart_tx pin of the charging box main control chip, and the second switch tube 162 has a third switch tube connection end, a fourth switch tube connection end for connecting with a uart_rx pin of the charging box main control chip, and a second switch tube control end for connecting with a first charging contact of the charging box;
the first switch tube connecting end is connected with the third switch tube connecting end and is grounded, the second switch tube connecting end is connected with the second switch tube control end, the resistor R7 is provided with a first resistor connecting end and a second resistor connecting end for connecting a power supply VCC, the first resistor connecting end is connected with the fourth switch tube connecting end, and the second resistor connecting end is connected with the second switch tube control end through a resistor R10;
the second communication circuit 25 includes a third switching tube 251, a fourth switching tube 252, and a resistor R8;
the third switch tube 251 has a fifth switch tube connection end, a sixth switch tube connection end for connecting with a uart_rx1 pin of the bluetooth headset main control chip, and a third switch tube control end for connecting with a third charging contact of the bluetooth headset, and the fourth switch tube 252 has a seventh switch tube connection end, an eighth switch tube connection end, and a fourth switch tube control end for connecting with a uart_tx1 pin of the bluetooth headset main control chip;
the eighth switching tube connecting end is connected with the third switching tube control end, the fifth switching tube connecting end is connected with the seventh switching tube connecting end and grounded, the resistor R8 is provided with a third resistor connecting end and a fourth resistor connecting end used for connecting a power supply VCC, and the third resistor connecting end is connected with the sixth switching tube connecting end.
The first switch tube 161 is an NMOS tube Q2 or an NPN triode Q2, and the second switch tube 162 is an NMOS tube Q4 or an NPN triode Q4;
the grid electrode of the NMOS tube Q2 is a first switching tube control end, the source electrode of the NMOS tube Q2 is a first switching tube connecting end, and the drain electrode of the NMOS tube Q2 is a second switching tube connecting end;
the base electrode of the NPN triode Q2 is a first switching tube control end, the emitter electrode of the NPN triode Q2 is a first switching tube connecting end, and the collector electrode of the NPN triode Q2 is a second switching tube connecting end;
the grid electrode of the NMOS tube Q4 is a second switching tube control end, the source electrode of the NMOS tube Q4 is a third switching tube connecting end, and the drain electrode of the NMOS tube Q4 is a fourth switching tube connecting end;
the base electrode of the NPN triode Q4 is a second switching tube control end, the emitter electrode of the NPN triode Q4 is a third switching tube connecting end, and the collector electrode of the NPN triode Q4 is a fourth switching tube connecting end.
The third switch tube 251 is an NMOS tube Q8 or an NPN triode Q8, and the fourth switch tube 252 is an NMOS tube Q9 or an NPN triode Q9;
the grid electrode of the NMOS tube Q8 is a third switching tube control end, the source electrode of the NMOS tube Q8 is a fifth switching tube connecting end, and the drain electrode of the NMOS tube Q8 is a sixth switching tube connecting end;
the base electrode of the NPN triode Q8 is a third switching tube control end, the emitter electrode of the NPN triode Q8 is a fifth switching tube connecting end, and the collector electrode of the NPN triode Q8 is a sixth switching tube connecting end;
the grid electrode of the NMOS tube Q9 is a fourth switching tube control end, the source electrode of the NMOS tube Q9 is a seventh switching tube connecting end, and the drain electrode of the NMOS tube Q9 is an eighth switching tube connecting end;
the base electrode of the NPN triode Q9 is a fourth switching tube control end, the emitter electrode of the NPN triode Q9 is a seventh switching tube connecting end, and the collector electrode of the NPN triode Q9 is an eighth switching tube connecting end.
The following describes an entire real wireless bluetooth headset charging system as an example:
the utility model provides a real wireless bluetooth headset charging system, including bluetooth headset charging box circuit 10, two-way communication circuit and bluetooth headset circuit 20, wherein:
the two-way communication circuit is a two-way communication circuit of the real wireless Bluetooth headset charging system and comprises a first communication circuit 16 and a second communication circuit 25;
the bluetooth headset charging box circuit 10 comprises a first battery 11, a DC/DC conversion circuit, a first charging switch unit 13, a first port 14 (here, the first charging contact of the charging box), a second port 15, and a charging box main control circuit;
the first battery 11 is connected with an input end of a DC/DC conversion circuit, an output end of the DC/DC conversion circuit is respectively connected with a first port 14 and a second port 15 through a first charging switch unit 13, the first communication circuit 16 is connected with the first port 14, and the charging box main control circuit is respectively connected with the DC/DC conversion circuit, the first charging switch unit 13 and the first communication circuit 16. Preferably, the first battery 11 is a rechargeable battery, and further comprises a charging interface 17 for charging the first battery 11, wherein two ends of the charging interface 17 are respectively connected with the positive electrode and the negative electrode of the first battery 11. Preferably, the charging interface 17 is a USB charging interface 17.
The bluetooth headset circuit 20 includes a second battery 21, a second charging switch unit 22, a bluetooth headset main control circuit, a third port 23 detachably connected to the first port 14 (here, a third charging contact of the bluetooth headset), and a fourth port 24 detachably connected to the second port 15, wherein the second battery 21 is a rechargeable battery, the second battery 21 is respectively connected to the third port 23 and the fourth port 24 through the second charging switch unit 22, the second communication circuit 25 is connected to the third port 23, and the bluetooth headset main control circuit is respectively connected to the second charging switch unit 22 and the second communication circuit 25, and is also connected to the second battery 21 to monitor a charging voltage of the second battery 21;
the charging box main control circuit is connected with the Bluetooth headset main control circuit through the first communication circuit 16 and the second communication circuit 25.
IN this embodiment, the charging box main control circuit includes a charging box main control chip U2, where the charging box main control chip U2 has a GPIO1 pin, an adc_in1 pin, a GPIO2 pin, an adc_in2 pin, a uart_rx pin, and a uart_tx pin;
the GPIO1 pin and the ADC_In1 pin are respectively connected with the DC/DC conversion circuit, the GPIO2 pin and the ADC_In2 pin are respectively connected with the first charging switch unit 13, and the UART_RX pin and the UART_TX pin are respectively connected with the first communication circuit 16.
In this embodiment, the first charging switch unit 13 includes a fifth switch tube and a resistor R6, and the output end of the DC/DC conversion circuit includes a first output end and a second output end;
the first output end is connected with the second end of the fifth switching tube, the second end of the fifth switching tube is connected with the control end of the fifth switching tube through a resistor R6, the control end of the fifth switching tube is connected with the GPIO2 pin, the first port 14 is connected with the first end of the fifth switching tube, and the first end of the fifth switching tube is connected with the ADC_In2 pin.
The output end of the DC/DC conversion circuit is connected with the charging box main control circuit through a current sampling circuit 121 and a voltage sampling circuit 122 respectively. In this embodiment, the DC/DC conversion circuit includes a DC/DC chip U1, a fifth switching tube, an inductor L1, a diode D1, a capacitor C2, a capacitor C3, a capacitor C4, a resistor R1, a resistor R2, a resistor R3, a resistor R4, and a resistor R5;
the DC/DC chip U1 is provided with a first pin to an eighth pin, the anode and the cathode of the first battery 11 are connected with a capacitor C1 in parallel, the eighth pin is connected with the anode of the first battery 11, one end of the inductor L1 is connected with the eighth pin, the other end of the inductor L1 is connected with the anode of the diode D1, the first end of the fifth switching tube is connected with the anode of the diode D1, the sixth pin is connected with the control end of the fifth switching tube, the cathode of the diode D1 is grounded through a capacitor C3, and the cathode of the diode D1 is connected with the first pin through a capacitor C4;
the input end comprises a first input end and a second input end, the first input end is an eighth pin, the fourth pin is a second input end, the non-series node of the resistor R4 is a first output end, and the first pin is a second output end.
The current sampling circuit 121 includes a sampling resistor R3, one end of the sampling resistor R3 is grounded, the other end of the sampling resistor R3 is connected to an adc_in1 pin of the charging box main control circuit, and the first pin is connected to the other end of the sampling resistor R3 and is connected to the second port 15;
the voltage sampling circuit 122 includes a sampling resistor R4 and a sampling resistor R5 connected IN series, the cathode of the diode D1 is connected to a non-series node of the sampling resistor R4, the series node of the sampling resistor R4 and the sampling resistor R5 is connected to a third pin, and the non-series node of the sampling resistor R5 is connected to an adc_in1 pin of the charging box main control circuit;
the second ends of the fourth pin, the fifth pin and the fifth switch tube are all connected with the negative electrode of the first battery 11 and grounded; the GPIO1 pin is connected with a seventh pin, the seventh pin is grounded through a resistor R2, and the second pin is grounded through a capacitor C2 and a resistor R1.
In this embodiment, the bluetooth headset main control circuit includes a bluetooth headset main control chip U3, where the bluetooth headset main control chip U3 has a VBAT pin, a GPIO pin, a uart_rx1 pin, and a uart_tx1 pin;
the VBAT pin is connected to the positive electrode of the second battery 21, the GPIO pin is connected to the second charging switch unit 22, and the uart_rx1 pin and the uart_tx1 pin of the bluetooth headset main control chip U3 are respectively connected to the second communication circuit 25.
The second charging switch unit 22 includes a sixth switch tube, a seventh switch tube, an eighth switch tube, a resistor R9, and a resistor R11; the third port 23 is connected to the first end of the sixth switching tube, the first end of the sixth switching tube is connected to the control end of the eighth switching tube through a resistor R9, the control end of the eighth switching tube is connected to the GPIO pin, the fourth port 24, the second end of the eighth switching tube and the negative electrode of the second battery 21 are all grounded, and the first end of the seventh switching tube is connected to the positive electrode of the second battery 21;
the second end of the sixth switching tube and the second end of the seventh switching tube are both connected with the first end of the eighth switching tube through a resistor R11, and the control end of the sixth switching tube and the control end of the seventh switching tube are both connected with the first end of the eighth switching tube.
The following generally describes the working principle of the present embodiment:
when the bluetooth headset is placed in the bluetooth headset charging box, the metal pins are in electrical contact with the corresponding metal contacts, i.e. the first port 14 of the bluetooth headset charging box circuit 10 is connected with the third port 23 of the bluetooth headset circuit 20, and the second port 15 of the bluetooth headset charging box circuit 10 is connected with the fourth port 24 of the bluetooth headset circuit 20.
The power VCC is transmitted to the control end of the third switching tube sequentially through the resistor R10, the first port 14 and the third port 23, and the third switching tube is turned on; at this time, if the second battery 21 still has power, the potential of the uart_rx1 pin of the bluetooth headset main control chip U3 is changed from high to low, and then the bluetooth headset main control chip U3 detects the current battery power of the second battery 21 through the VBAT pin.
After the current battery power of the second battery 21 is detected, the uart_tx1 pin of the bluetooth headset main control chip U3 sends a first information instruction (meanwhile, the uart_rx1 pin of the bluetooth headset main control chip U3 also receives the first information instruction, but does not perform any processing), and the first information instruction is transmitted to the control end of the second switching tube through the fourth switching tube, the third port 23 and the first port 14 in sequence, the second switching tube is conducted or leaked to the ground, and then the uart_rx pin of the charging box main control chip U2 can receive the first information instruction.
Then, the charging box main control chip U2 starts to initialize, reads the battery power, the temperature and the circuit states of each part of the first battery 11, and after confirming that the problem exists, the uart_tx pin of the charging box main control chip U2 sends a second information instruction, the second information instruction is sequentially transmitted to the control end of the third switch tube through the first switch tube, the first port 14 and the third port 23, the third switch tube is turned on, the potential of the uart_rx1 pin of the bluetooth headset main control chip U3 is changed from high to low, that is, the bluetooth headset main control chip U3 can receive the second information instruction, and the information interaction between the charging box main control chip U2 and the bluetooth headset main control chip U3 is completed. It should be noted that, if the bluetooth headset main control chip U3 is still connected with the mobile terminal bluetooth, the mobile terminal may also receive the information about the battery power, the temperature and the status of each part of the circuit of the first battery 11.
Under the condition that the Bluetooth headset charging box circuit 10 and the Bluetooth headset circuit 20 are not problematic, the GPIO pin of the Bluetooth headset main control chip U3 outputs a high potential to the control end of the eighth switching tube, the eighth switching tube is conducted, then the sixth switching tube and the seventh switching tube are sequentially conducted, and the conduction of the second charging switch unit 22 is completed. Then, the uart_tx1 pin of the bluetooth headset main control chip U3 issues a third information command (meanwhile, the uart_rx1 pin of the bluetooth headset main control chip U3 also receives the third information command, but does not perform any processing), and the third information command is sequentially transmitted to the control end of the second switching tube through the fourth switching tube, the third port 23 and the first port 14, and the second switching tube is turned on or turned on and off to the ground, so that the uart_rx pin of the charging box main control chip U2 can receive the third information command.
After receiving the third information instruction, the charging box main control chip U2 controls the DC/DC chip U1 to be turned on through the GPIO1 pin, and controls the fifth switch tube to be turned on through the GPIO2 pin, so as to complete charging initialization and start charging the second battery 21. IN the process of charging the second battery 21, the charging box main control chip U2 monitors the voltages at two ends of the sampling resistor R3 through the ADC_In1 pin, so as to monitor the charging current, and the real-time charging voltages at two ends of the second battery 21 are collected from the VBAT pin by the Bluetooth headset main control chip U3 and sequentially reported to the charging box main control chip U2 through the fourth switching tube, the third port 23, the first port 14 and the second switching tube. When the charging current falls to 0.1C of the preset current, the DC/DC chip U1, the fifth switching tube, the sixth switching tube and the seventh switching tube are sequentially turned off, and the charging of the second battery 21 is completed.
When the bluetooth headset is placed in the bluetooth headset charging box, if the second battery 21 does not have electric quantity, the charging box main control chip U2 can not receive the information instruction sent by the bluetooth headset main control chip U3, at this time, the charging box main control chip U2 can control the DC/DC chip U1 and the fifth switch tube to be opened, the second battery 21 is charged first, the bluetooth headset main control chip U3 can be electrified to work, and then the battery electric quantity of the second battery 21 can be checked.
In this embodiment, the first switching tube is an NMOS tube Q2, the second switching tube is an NMOS tube Q4, the fourth switching tube is an NMOS tube Q9, the third switching tube is an NMOS tube Q8, the eighth switching tube is an NMOS tube Q7, and the fifth switching tube is an NMOS tube Q1, however, the first switching tube, the second switching tube, the fourth switching tube, the third switching tube, the eighth switching tube, and the fifth switching tube may also be NPN transistors (collector corresponds to drain, base corresponds to gate, and emitter corresponds to source);
the fifth switching tube is a PMOS tube Q3, the sixth switching tube is a PMOS tube Q5, and the seventh switching tube is a PMOS tube Q6, however, the fifth switching tube, the sixth switching tube, and the seventh switching tube may be PNP transistors (collector corresponds to drain, base corresponds to gate, and emitter corresponds to source).
Next, the difference between the charge conversion efficiency of the present embodiment and the charge conversion efficiency of the related art will be roughly described.
The charge conversion efficiency of the present embodiment is as follows: assuming that the internal resistance of the inductor L1 is 0.1 ohm, the forward voltage drop of the diode D1 is 0.15 volt, the internal resistance of all switching tubes is 50 milliohms, the charging current is 0.1 ampere, the voltage of the first battery 11BT1 is 3.7 volts, and the voltage of the second battery 21 is 3.0 volts (here, the lowest battery voltage V6 and the lowest efficiency state). Defining the voltage between the source electrode and the drain electrode of the PMOS tube Q3 as a first voltage V1, defining the voltage between the source electrode and the drain electrode of the PMOS tube Q5 as a second voltage V2, defining the voltage between the source electrode and the drain electrode of the PMOS tube Q6 as a third voltage V3, defining the voltage at two ends of the sampling resistor R3 as a fourth voltage V4, defining the forward voltage drop of the diode D1 as a fifth voltage V5, defining the total output power as the total output power P1, defining the power of the inductor L1 as the power P2, defining the power of the NMOS tube Q1 as the power P3, defining the input power as the input power P4, defining the input current as the current I1, defining the current passing through the inductor L1 as the current I2, and defining the current passing through the NMOS tube Q1 as the current I3;
v1=v2=v3=0.1 amperes times 0.01 ohm=0.001 volt; v4=0.1 amperes times 0.01 ohm=0.001 volts;
the total output power P1 is the product of the total output voltage and the charging current, wherein the total output voltage is the sum of V1, V2, V3, V4, V5 and V6, and the charging current is 0.1 ampere.
Thus, the output total power:
P1=（V6+V1+V2+V3+V4+V5）*0.1
=（3+0.005+0.005+0.005+0.001+0.15）*0.1
= 0.3166 watts.
From the law of conservation of energy: p4=p2+p3+p1, wherein p4=3.7×i1;
thus, 3.7×i1= (square of I2×0.1) + (square of I3×0.1) +0.3166 watts.
In the input boost circuit, the first battery 11, the inductor L1 and the NMOS transistor Q1 are connected in series, so i1=i2=i3= 0.089183 amperes;
total efficiency: (3.0 volts times 0.1 amperes) divided by (3.0 volts times 0.089183 amperes) =90.91%.
The charging conversion efficiency of the prior art is as follows:
under the same condition, the existing Bluetooth earphone is in linear charging, the current in the whole loop is 0.1 ampere, the output of DC/DC is always 5.0 volts, the total power of the output is defined as P0, the input current is defined as I0, the current passing through an inductor L1 is defined as I21, and the current passing through an NMOS tube Q1 is defined as I31; defining the forward voltage drop of diode D1 to be voltage V0 and 0.15 volts;
the charge conversion efficiency is calculated as follows:
the total output power is
Pex= (5.0 volts+v0) times 0.1 amps= (5+0.15) times 0.1 amps = 0.515 watts;
in this case, the current in the DC/DC input boost loop is:
i0 =i21=i31= 0.1450705 amperes;
the total efficiency is as follows:
(3.0 volts by 0.1 ampere) divided by (3.7 volts by 0.1450705 ampere) =55.89%, so that the circuit efficiency of this embodiment can be improved to the highest degree: 90.91% -55.89% = 35%.
It should be noted that, in this embodiment, only the step-down or step-up is performed during the energy conversion process, and no step-up or step-down exists at the same time. Meanwhile, in the embodiment, the charging box main control chip U2 is used for controlling the opening of the DC/DC chip U1 and the fifth switching tube, so that the charging efficiency can be improved to more than 90%. In addition, the second charging switch unit 22 is turned on only when charging. Only the internal resistances of the sixth switching tube and the seventh switching tube in the second charging switch unit 22 in the bluetooth headset terminal cause loss, and the bluetooth headset main control chip U3 and the charging box main control chip U2 of the present embodiment consume power, but the loss of both the bluetooth headset main control chip U3 and the charging box main control chip U2 can be ignored.
The invention has the design key points that the first communication circuit is mainly connected with the second communication circuit through the first charging contact and the third charging contact, the first charging contact and the third charging contact are multiplexed, single-wire bidirectional communication between the charging box and the Bluetooth headset is realized, an additional communication line is not needed, the design cost of the circuit is reduced, the circuit has better economic benefit, and the charging box or the Bluetooth headset can receive the signal sent by the charging box or the Bluetooth headset when sending the signal by the charging box or the Bluetooth headset, so that the condition of the signal sent by the charging box or the Bluetooth headset is convenient to know;
and the whole circuit structure is ingenious and reasonable in design, and each circuit is stable in performance, safe and reliable.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the technical scope of the present invention, so that any minor modifications, equivalent changes and modifications made to the above embodiments according to the technical principles of the present invention still fall within the scope of the technical solutions of the present invention.
Claims (2)
1. A two-way communication circuit of a real wireless Bluetooth headset charging system is characterized in that: the Bluetooth headset comprises a first communication circuit positioned in a Bluetooth headset charging box and a second communication circuit positioned in the Bluetooth headset;
the first communication circuit is connected with the second communication circuit through the first charging contact and the third charging contact, the first communication circuit comprises a first switching tube, a second switching tube, a resistor R10 and a resistor R7, the first switching tube is provided with a first switching tube connecting end, a second switching tube connecting end and a first switching tube control end for connecting with a UART_TX pin of a main control chip of the charging box, and the second switching tube is provided with a third switching tube connecting end, a fourth switching tube connecting end for connecting with a UART_RX pin of the main control chip of the charging box and a second switching tube control end for connecting with the first charging contact of the charging box;
the first switch tube connecting end is connected with the third switch tube connecting end and is grounded, the second switch tube connecting end is connected with the second switch tube control end, the resistor R7 is provided with a first resistor connecting end and a second resistor connecting end for connecting a power supply VCC, the first resistor connecting end is connected with the fourth switch tube connecting end, and the second resistor connecting end is connected with the second switch tube control end through a resistor R10;
the second communication circuit comprises a third switching tube, a fourth switching tube and a resistor R8,
the third switching tube is provided with a fifth switching tube connecting end, a sixth switching tube connecting end for connecting with a UART_RX1 pin of the Bluetooth headset main control chip and a third switching tube control end for connecting with a third charging contact of the Bluetooth headset, and the fourth switching tube connecting end Guan Juyou is provided with a seventh switching tube connecting end, an eighth switching tube connecting end and a fourth switching tube control end for connecting with a UART_TX1 pin of the Bluetooth headset main control chip;
the eighth switching tube connecting end is connected with the third switching tube control end, the fifth switching tube connecting end is connected with the seventh switching tube connecting end and is grounded, the resistor R8 is provided with a third resistor connecting end and a fourth resistor connecting end for connecting a power supply VCC, and the third resistor connecting end is connected with the sixth switching tube connecting end;
the first switching tube is an NMOS tube Q2 or an NPN triode Q2, and the second switching tube is an NMOS tube Q4 or an NPN triode Q4.
2. The two-way communication circuit of a true wireless bluetooth headset charging system of claim 1, wherein: the third switching tube is an NMOS tube Q8 or an NPN triode Q8, and the fourth switching tube is an NMOS tube Q9 or an NPN triode Q9;
the grid electrode of the NMOS tube Q8 is a third switching tube control end, the source electrode of the NMOS tube Q8 is a fifth switching tube connecting end, and the drain electrode of the NMOS tube Q8 is a sixth switching tube connecting end;
the base electrode of the NPN triode Q8 is a third switching tube control end, the emitter electrode of the NPN triode Q8 is a fifth switching tube connecting end, and the collector electrode of the NPN triode Q8 is a sixth switching tube connecting end;
the grid electrode of the NMOS tube Q9 is a fourth switching tube control end, the source electrode of the NMOS tube Q9 is a seventh switching tube connecting end, and the drain electrode of the NMOS tube Q9 is an eighth switching tube connecting end;
the base electrode of the NPN triode Q9 is a fourth switching tube control end, the emitter electrode of the NPN triode Q9 is a seventh switching tube connecting end, and the collector electrode of the NPN triode Q9 is an eighth switching tube connecting end.
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