The fire emergency power supply EPS in important buildings is relatively complete and has high power. It is often used as the power supply system for fire elevators, alarm systems, and smoke exhaust fan systems. Therefore, it can be used as the power supply for conventional and emergency lighting dual-purpose LED energy-saving lighting systems, while gasoline generates electricity. The unit is only used as a supplement when the power of the EPS system is exhausted when the power is cut off for a long time. According to the requirements of system design, combined with the actual situation, the system block diagram is shown in Figure 1.

1 System Design

The fire emergency power supply EPS in important buildings is relatively complete and has high power. It is often used as the power supply system for fire elevators, alarm systems, and smoke exhaust fan systems. Therefore, it can be used as the power supply for conventional and emergency lighting dual-purpose LED energy-saving lighting systems, while gasoline generates electricity. The unit is only used as a supplement when the power of the EPS system is exhausted when the power is cut off for a long time. According to the requirements of system design, combined with the actual situation, the system block diagram is shown in Figure 1.

Design of LED Emergency Lighting Controller Based on MSP430

The system includes EPS power supply components, LED lighting system and control room control system. The EPS power supply system is the backup power supply part of the system, and its main functions are electric energy storage and power switching; the LED lighting system is mainly composed of a rectifier filter circuit, an LED drive circuit, and an LED light group. The LED constant current source circuit is the driving part that provides the constant current of the LED light group. It also includes wired and wireless interface parts, which receive control signals from the control room and adjust the brightness of the LED lights. The control system in the control room includes the operation panel, the processor MCU part, as well as wired and wireless interfaces, mainly human-computer interaction and dimming control command output.

2 Controller hardware design

The controller is mainly installed in the control room, detects the working status of each LED light by wired and wireless methods, and uses the button operation to remotely control the LED light to work in three working modes: low power consumption, energy saving, emergency, and special occasions. Remote shutdown operation.

Design of LED Emergency Lighting Controller Based on MSP430

With MSP430 microcontroller as the control core, the system control sending and receiving end devices are designed, as shown in Figure 2. The sending end of the controller is mainly installed in the control room, and the human-computer interaction is realized through the operation panel, while the receiving end is connected to the constant current source, receives the control command from the sending end, sends out PWM signals with different duty ratios, and controls the constant current source to adjust the LED light group. Drive LEDs to work in different states.

Design of LED Emergency Lighting Controller Based on MSP430

CC2500 is a single-chip 2.4 GHz transceiver. It establishes contact with the MCU through the SPI interface. The MCU needs to complete the configuration of the CC2500 register at the beginning, and its read and write sequence is shown in Figure 3. First, set up registers such as IOCFG2, IOCFG0.TX to send the number of bytes, packet length, and transmit power to complete the initialization of CC2500.

3 Controller software design

The design of the system software is mainly the initialization of the MSP430F2249 and the setting of the radio frequency chip CC2500 register, as well as the read and write operations of transmitting and receiving data. Call the BSP, MRFI, NWK, NWK APPLI CATION in the SimpliciTI protocol stack, where the BSP is the most basic board-level hardware, and the MCU initializes the CC2500 function and the LED and button operation functions; MRFI belongs to the radio frequency interface layer and provides the choice of radio frequency chips. The configuration parameters of the radio frequency chip, the driver of the radio frequency chip and the communication interface, NWK and NWK_APPLICATION are the network layer and the network application layer, which belong to the content of the SimpliciTI protocol stack, including the establishment of the network, the allocation of the network address, the network data frame structure, and the data message queue. , data message processing, network communication security encryption and a series of complex mechanisms, through simple function calls to achieve basic hardware operations. The software design flow chart of the transmitter and receiver of the wireless transceiver is shown in Figure 4.

Design of LED Emergency Lighting Controller Based on MSP430

At the receiving end, by opening the internal timer Timer_B, according to the different data received, adjust the timing period of Timer_B, and set the number and reset through the ordinary I/O port to output different duty ratios of 10%, 50%, 90%, so that LED lights work in three working modes: low power consumption, energy saving and emergency.

The subroutine code of the sending end MSP430 microcontroller to transmit data to CC2500 is:

Design of LED Emergency Lighting Controller Based on MSP430

Where msg is the sending buffer, SMPL_Send is the sending data function, once the sending is successful, it returns SMPL_SUCCESS.

The receiver calls the simpliciTI protocol function, and the code to accept the CC2500 cached data is:

Design of LED Emergency Lighting Controller Based on MSP430

Among them, msg is the receive buffer, and SMPL_Reeeive is the function of receiving data. Once the reception is successful, it returns SMPL_SUCCESS.

4 Constant current source driver design

The constant current source driver consists of an integrated operational amplifier 7LM358 and a power supply chip 8XL4016, as shown in Figure 5. The XL4016 is a 180 kHz fixed frequency PWM step-down DC-DC converter, 8 A current load, 36VDC input, and the output voltage value is determined by diode D2 to 30 V, which limits the number of LED lights in series. Since the voltage drop of the light-emitting LED lamps is 3.3 V each, this makes the output voltage up to 3.3×9=29.7 V. Based on redundancy considerations, the system uses 8 LEDs to output in series, that is, 3.3×8=26.4 V.

Design of LED Emergency Lighting Controller Based on MSP430

The system uses a digital-to-analog converter DAC7611 to output a constant reference voltage. After power-on, the microcontroller adjusts the corresponding value of its input, so that the output value of the DAC761 is AOUT=1.25 V, and the load of the driver is:

Design of LED Emergency Lighting Controller Based on MSP430

Due to insufficient RCS accuracy, there is a certain deviation between the output current and the set value of 3 A. Normally, by adjusting the size of RCS, the current of the constant current source can be adjusted. However, if one or more LEDs in the LED light group age or fail, the system needs to detect and automatically adjust the current of the constant current source, so the microcontroller needs to read the feedback value and adjust AOUT. A 1 W LED has a voltage drop of about 3.3 V and a current of 300 mA, so there is

Design of LED Emergency Lighting Controller Based on MSP430

In the same way, it can be obtained that A1~A7 are all 0.2 V, which is the basis for adjusting AOUT. Once a certain LED light is damaged, the entire string of LEDs will stop working.

Ao=IloadRCS=0.1 V (3)

At this time, the MCU reads and adjusts the Ao feedback value, adjusts AOUT to 1 V, and makes Iload=2.7 A, so as to ensure that the remaining lamp brightness remains constant.

5 Conclusion

The system can provide a set of lighting solutions for large-span spaces such as workshops, waiting halls, stadiums, conference halls, etc., and can realize automatic switching of conventional and emergency lighting. , live broadcast and other activities as normal. The system has the characteristics of flexibility, energy saving and long service life. The wireless controller with MSP430 as the control core can realize wireless dimming in a space of 50 m, making it work in three modes: regular, energy-saving and emergency.

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