A kind of method for managing power supply of board unitsTechnical field
The present invention relates to the method for managing power supply of wireless telecommunications system in a kind of intelligent transportation field, particularly relate to a kind of implementation method of board units electric power management circuit.
Background technology
In highway tolling system, non-parking charge (ETC) because its operation is convenient and efficient, more and more is subjected to the favor and the popularization of international market as a kind of novel charge method at present.This charge method is generally finished identification, charge and the statistical work by vehicle on the track automatically by means of infrared or microwave technology, and charge efficient height can solve the situation that charge station's vehicle blocks up effectively.ETC still is in the starting stage at home, but will become the inexorable trend of future development.
In the ETC system, OBU (On Board Unit board units) generally adopts powered battery, and selects lithium-sulphurous acid chlorine (Li-SOCl2 Battery) battery of not reproducible charging for use.It has following characteristics: discharge is pressed high; Discharge curve is very smooth; The low-temperature operation function admirable; Year self-discharge rate is low; Storage life is long.Adopt this powered battery to save the worry of battery recharge, but also have problems:
1. the battery utilization factor is not high: the consumption of back along with battery capacity works long hours, powered battery voltage reduces, even be lower than some device or module, the minimum of IC-card module for reading and writing for example, yet this moment, battery still existed a large amount of capacity to be not used, and caused the battery capacity utilization factor to reduce.
2. carrying load ability is poor: for large current load, IC-card module for reading and writing for example is after DSRC (Dedicated Short Range Communications) chip etc. is started working, the cell voltage amplitude of oscillation is bigger, can not guarantee constant voltage output, to making some device or module, for example the IC-card module for reading and writing can't operate as normal.
3. standby current (electric current under the sleep pattern) is excessive: OBU overwhelming majority time service is in sleep pattern in the whole life of OBU, yet the working current during the sleep pattern is difficult to again be controlled in the scope that is allowed, therefore cause the waste for no reason of the big energy of battery, thus the serviceable life of reducing product.
Summary of the invention
For solving the existing in prior technology problem, the invention provides a kind of method for managing power supply of board units, it can effectively improve the utilization factor and the carrying load ability of battery, reduces the standby current of product, strengthens the serviceable life of product.
The method for managing power supply of board units of the present invention is MCU (microcontroller), the wake-up circuit in the 5.8G microwave module and safety check electric routing battery continued power in the board units; Described OBU has two kinds of mode of operations, sleep pattern and enable mode, and under enable mode, MCU can make it enter sleep pattern by software instruction, and under sleep pattern, MCU can make it enter enable mode by the interruption that activates; IC-card module for reading and writing, DSRC chip, man-machine interface circuit, the power supply of the low-voltage testing circuit of modulation/demodulation circuit in the 5.8G microwave module and MCU inside only just begin power supply under enable mode.
The power supply of IC-card module for reading and writing, DSRC chip is controlled by the DC/DC circuit, MCU realizes the switch control of DC/DC circuit by the work enable pin of its delivery outlet control DC/DC circuit, when the unlatching DC/DC of MCU pin output high level, then the DC/DC circuit begins power supply, and output 3.3V voltage, when the unlatching DC/DC of MCU pin output low level, then the DC/DC circuit turn-offs and stops voltage output.
The present invention adopts software instruction to make MCU before entering sleep pattern it be opened RF output pin output high level, and all the other output pin output low levels are to prevent that the MCU output pin is to the caused power consumption of the power supply of power cutoff chip; Adopt software instruction to make to wake interrupt request singal up and the corresponding MCU input pin of safety check interrupt request singal interrupt function before entering sleep pattern enables, so that MCU can be under sleep pattern be waken up by interrupting; At enable mode, MCU is for the module that can select the visit of inquiry mode and interrupt mode, and for example interrupt mode is adopted in the operation of DSRC chip and IC-card module for reading and writing, the power consumption that the bus change is caused when reducing inquiry mode to outside module accesses; On hardware circuit, adopt the DC/DC circuit to give the power supply of the large current loads such as modulation-demodulation circuit in IC-card module for reading and writing, DSRC chip, man-machine interface circuit, the 5.8G microwave module, improved carrying load ability and the battery utilization factor of OBU effectively; Adopt the analog to digital converter (AD) of MCU inside and only under enable mode, carry out battery voltage detection, with further reduction hardware cost and power consumption.
In sum, the method for managing power supply of board units of the present invention is with the core devices of MCU as power management, the method that adopts hardware circuit and software control to combine, the utilization factor and the carrying load ability of battery have been improved effectively, reduce the standby current of product, strengthened the serviceable life of product.
Description of drawings
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail:
Accompanying drawing is the structural drawing of the method for managing power supply of a kind of board units of the present invention.
Embodiment
As shown in the figure, the method for managing power supply of a kind of board units of the present invention is responsible for the OBU all functions are carried out unified management by MCU U8, comprising power management.For the power management of OBU, but MCU mainly realizes by the power switch of the control mode switch of OBU and power cutoff chip or module.
The mode of operation of OBU is controlled by MCU, and described OBU has two kinds of mode of operations, sleep pattern and enable mode, under enable mode, MCU can make it enter sleep pattern by software instruction, and under sleep pattern, MCU can make it enter enable mode by the interruption that activates.For realizing OBU waking up from the sleep pattern to the enable mode, OBU is before entering sleep pattern, MCU enables the input pin interrupt function of wake-up interrupts request signal and the corresponding MCU of safety check interrupt request singal, so that MCU can wake up by the interruption that activates under sleep pattern.In addition, OBU is before entering sleep pattern, and the unlatching RF output pin of MCU is exported high level, and all the other output pin output low levels are to prevent that the MCU output pin is to the caused power consumption of the power supply of power cutoff chip or module.Under enable mode, MCU adopts interrupt mode for the operation of the module that can select the visit of inquiry mode and interrupt mode, the power consumption that the bus change is caused when reducing inquiry mode to outside module accesses, for example the interrupt request of MCU by DSRC interrupt request singal and IC-card module interrupt request singal realizes the interruption visit to DSRC and IC module for reading and writing.IC-card module for reading and writing U5, DSRC chip U6, man-machine interface circuit U 9, the power supply of the modulation/demodulation circuit among the 5.8G microwave module U3 and the low-voltage testing circuit of MCU inside only just begins power supply under enable mode.
But the power switch of power cutoff chip or module is MCU to be controlled by delivery outlet.The power supply of IC-card module for reading and writing U5, DSRC chip U6 is by 7 controls of DC/DC circuit U.MCU realizes the switch control of DC/DC circuit U 7 by the work enable pin of its delivery outlet control DC/DC circuit U 7, and when the unlatching DC/DC of MCU pin output high level, then DC/DC circuit U 7 begins power supply, and output 3.3V voltage; When the unlatching DC/DC of MCU pin output low level, then DC/DC circuit U 7 is turn-offed and is stopped voltage output.
The power supply of man-machine interface circuit U 9 is controlled jointly by DC/DC circuit and switching tube Q2, at first, the unlatching DC/DC pin output high level of MCU makes the DC/DC circuit that voltage output be arranged, the unlatching man-machine interface pin of MCU is exported high level then, switching tube Q2 is opened, above any one does not satisfy in two conditions, the power supply of then man-machine interface circuit U 9 disconnects.
5.8G the power supply of the modulation/demodulation circuit among the microwave module U3 is by switching tube Q1 control, when the unlatching RF of MCU pin output low level, then switching tube Q1 opens, the power connection of modulation/demodulation circuit among the 5.8G microwave module U3; When the unlatching RF of MCU pin output high level, then switching tube Q1 closes, and the power supply of modulation/demodulation circuit disconnects among the 5.8G microwave module U3.
The present invention adopts software instruction to make the DC/DC circuit, and switching tube Q1, Q2 turn-off before entering sleep pattern, stop the power supply to modulation-demodulation circuit among IC-card module for reading and writing, DSRC chip, man-machine interface circuit and the 5.8G microwave module U3, to reduce the OBU standby current.
In the ETC system, the OBU most of the time all is in sleep pattern, has only after the vehicle that OBU equipment is installed enters roadside equipment (RSU) transaction communications zone, and ability and RSU carry out communication.Therefore, require OBU to have the function whether the identification vehicle enters the RSU communications zone, this function realizes by the wake-up circuit among the 5.8G microwave module U3; In addition, also require function that OBU has a safety detection to prevent that OBU internal security data from illegally being stolen, this function realizes by safety check circuit U 2.The realization of two kinds of functions of the above OBU all has randomness, and therefore, this two parts functional circuit need be by battery U1 continued power.In addition, as the core devices MCU of whole OBU, also by battery U1 continued power.
The detection of cell voltage adopts the analog to digital converter (AD) of MCU inside to realize.MCU realizes the control that AD changes by the corresponding register of this AD converter of visit, and transformation result is converted to the correspondent voltage value.The detection of cell voltage is only carried out under enable mode, and before entering sleep pattern, the power supply that is turn-offed described AD converter by MCU is with further reduction OBU standby current.
For removing 5.8G microwave module U3 power supply, carry out filtering at the power input increase filtering circuit U4 of 5.8G microwave module U3, effectively 5.8G microwave module U3 power supply is isolated with the low-frequency channel power supply with influencing each other between the low-frequency power.