Communication power supply monitoring system based on Web microcontroller and CC430F6127

　　As the scale of communication networks continues to expand, the number of communication power supplies is also increasing, and the monitoring of communication power supplies has become more important. The power supply of communication base stations is generally in a relatively scattered state, and in most cases there is no one to guard it. In order to ensure real-time monitoring of communication power supplies, it is urgent to develop a system that can monitor communication power supplies in real time.

　　The communication power supply monitoring system is classified according to the data transmission method, including the monitoring system of telephone line communication, the monitoring system of GSM communication, and the monitoring system based on Web communication. The telephone line system requires a fixed line and is relatively expensive; GSM communication uses SMS channels to transmit data. If the amount of data to be transmitted is relatively large, the cost is also high; Web technology has relatively complete functions and superior performance, but the monitoring system based on Web communication needs to lay network lines. In the case of more scattered points, multiple Web sites need to be used, and the cost is also high. In view of the above shortcomings, a design scheme based on Web and single-chip microcomputer CC430F6127 is now adopted. CC430F6127 integrates CC1101 radio transceiver, which can realize wireless transmission of 100 meters. Each RF radio communication module can be used as a small repeater to realize indirect transmission and make the transmission distance longer. Using RF radio modules, a small local area network can be formed, and then multiple small networks are connected through the Web network to achieve the purpose of monitoring all communication power supplies. This not only reduces the use of Web sites, but also the low power consumption of CC430F6127 makes the use cost lower, meeting the application requirements.

　　1. Operation principle of communication power supply monitoring system

　　The main function of the communication power supply monitoring system is to monitor the power quality provided by the communication power supply and send the collected data to the monitoring center. The structural block diagram of the communication power supply monitoring system is shown in Figure 1. First, the communication power supply monitoring point will collect the power data and calculate and analyze it. Then, the data will be transmitted to the communication power supply monitoring sub-network center through the RF radio communication channel. The sub-network center will transmit all monitored data to the monitoring center through the Web network, realizing the purpose of monitoring all communication power supplies.

　　2 System Hardware Design

　　The hardware design of the communication power supply monitoring system is divided into data acquisition module, RF radio data transmission module and CC430F6127 and Web connection module at the center of the monitoring system sub-network. The main task of the data acquisition module is to collect the power data of the communication power supply and conduct relevant data analysis; the task of the RF radio module is to send the collected data to the center of the communication power supply sub-network; the role of the CC430F6127 and Web connection module is to transmit the data collected by the center of the communication power supply monitoring sub-network to the monitoring center through the Web network. The following is a detailed introduction to each module.

　　2.1 Data Acquisition Module

　　The data acquisition module needs to collect the voltage, current, temperature and other parameters of the communication power supply. The hardware circuit is shown in Figure 2. The data acquisition module is controlled by the single-chip microcomputer CC430F6127 (F6127 for short). First, the voltage and current of the communication power supply are converted by the Hall voltage sensor and the Hall current sensor respectively. The outputs of the two sensors are current signals. After the currents output by the two sensors pass through the R1 and R2 sampling resistors respectively, a voltage drop is formed at both ends of the resistors. Since one end of the resistor is grounded, the other end of the resistor VO is the converted voltage signal; then the voltage across the sampling resistors R1 and R2 is collected by AD7656, and the amplitude of the input voltage and current can be calculated according to the transformation ratio of the sensor; F6127 can calculate the maximum value and average value of the voltage and current and other parameters through relevant algorithms, and send this data to the monitoring center.

　　The AD7656 analog-to-digital conversion chip used in this system is a 16-bit successive approximation ADC with 6 channels sampling simultaneously. It can meet the requirements of high resolution, multi-channel, high conversion rate and low power consumption. It is mainly used in power monitoring systems, instrument control systems, etc. As shown in Figure 2, the positive power supply voltage VDD of AD7656 is +12 V, the negative power supply voltage VSS is -12 V, and the analog voltage AVCC, logic voltage VDRIVE and digital voltage DVCC are all +5V. The STBY of AD7656 is connected to VDRIVE to select the normal mode; the SER/PAR port is grounded to select the parallel interface; the W/B grounding indicates 16-bit parallel output; the RANGE port is grounded to select the input voltage range of ±10V; the WR/REFEN/DIS is connected to VDRIVE to select the internal reference. The P0 port of the single-chip microcomputer F6127 is connected to the parallel data ports DB0~DB15 of the AD7656 as a parallel data port. The P1.0 port is connected to the BUSY of the AD7656 to detect whether the conversion is completed; the P1.1 port is connected to the three ports CONVST A, CONVST B and CONVST C to control the AD7656 to sample 6 signals simultaneously; the P1.2 port is connected to the read signal RD of the AD7656 as the read data control port; the P1.3 port is connected to the /CS terminal of the AD7656 as the chip select port; the P1.4 port is connected to the RESET port of the AD7656 as the restart control port.

　　The communication power supply itself generates heat. Its temperature will affect the power supply performance of the power supply. Real-time measurement of the temperature of the communication power supply plays a very important role in better controlling the power supply of the power supply. In this system, the DS18B20 temperature acquisition chip is used to collect the temperature of the communication power supply. The DS18B20 is a high-speed, high-precision temperature sensor with a power supply voltage of 3.3 V; a measurement range of -55 to +125°C; and a measurement accuracy of 0.5°C. When installing the temperature sensor, the DS18B20 chip needs to be as close to the communication power supply as possible. The P1.5 port of the single-chip microcomputer CC430F5137 is connected to the DQ port of the DS18B20 to control the reading and writing operations of the DS18B20.

　　2.2 RF radio data transmission module

　　The RF radio data transmission device is composed of the CC1101 radio transceiver integrated in the CC430F6127 microcontroller. The CC430F6127 microcontroller is a product that combines TI's MSP430F6xx series MCU with a low-power RF transceiver. Extremely low current consumption can be achieved in low-power mode, and battery-powered wireless network applications can work continuously for more than 10 years. The advanced functions included in the micro-package can also provide core power for innovative RF sensor networks, which can report data to a central collection point. The CC430F6127 is a 16-bit ultra-low power MCU, the system supports a maximum clock frequency of 20 MHz, has 4 KB RAM, 32 KB Flash, 64 pins, CC1101 radio, and a supply voltage range of 1.8 to 3.6 V. The normal working mode consumes 160μA/MHz, and the LPM_3 consumes 2.0μA to PM_4 mode consumes 1.0μA.

　　The RF frequency of the CC1101 radio transceiver integrated in the CC430F6127 microcontroller has three ranges: 300-348 MHz, 389-464 MHz, and 779-928 MHz. According to the data sheet provided by TI and the system requirements, the RF frequency of this system is set to 433 MHz, the data packet length can reach 20 bytes, the data transmission rate is 38.4 kbps, and the maximum transmission power can reach 12.6 dBm. This system can adjust the transmission power according to the distance between the monitoring point and the center point of the monitoring subnetwork to achieve the purpose of low power consumption. The hardware circuit is shown in Figure 3. The power supply voltage of CC A30F6127 is +3.3 V, and the RF external crystal frequency is 26 MHz, where RF_N and RF_P are the receiving and transmitting pins of the RF radio transceiver. Two pins are external electronic devices and power antennas.

[page]

　　2.3 C430F6127 and Web connection module at the center of the monitoring system subnetwork

　　The CC430F6127 uses the network card chip CS8900A from Crystal Semiconductor to connect to the Web. It is a low-power Ethernet control chip. Its main internal functional modules include: serial EEPROM interface, ISA bus interface, ultra-high-speed cache RAM, complete analog front-end 10BASE-T and AUI interface, and IEEE 802.3 Ethernet MAC engine. CC430F6127 can directly control CS8900A through the I/O port, as shown in Figure 4. CS8900A uses 3.3V power supply voltage and the default working mode, that is, 8-bit data bus for reading and writing. P2.0~P2.3 ​​of CC430F6127 is connected to SA0~SA3 of CS8900A as the address bus, SA8 and SA9 are connected to high level, SA4~SA7 and SA10~SA19 are grounded, and its address is always 0300H when reset. P3.0~P3.7 of CC430F6127 is connected to SD0~SD7 of CS8900A as the data line, and the rest of the data lines of CS8900A are grounded. P4.0 port of CC430F6127 is connected to the port of CS8900A as the read control port, and P4.1 port of CC430F6127 is connected to the port of CS8900A as the write control port. Two external LED indicators are convenient for observing the data transmission status. In order to protect the system safety, an isolation transformer CL2246X is used between CS8900A and the RJ45 port for isolation connection to play the role of isolation protection.

　　3 System Software Design

　　The program flow of the communication power supply monitoring system is shown in Figure 5. First, the system is initialized, and the single-chip microcomputer CC430F6127 enters the low-power mode. If the monitoring center sends a control instruction to the monitoring point, the CC430F6127 single-chip microcomputer at the monitoring point will have an RF radio reception interrupt. This interrupt will wake up the single-chip microcomputer from the low-power mode to start judging the control instructions sent by the monitoring center and perform related operations, including the measurement of current, voltage, temperature and other functions. Then these parameters are sent to the monitoring center through the RF radio module. The communication power supply monitoring system not only needs to complete the function of detecting parameters, but also needs to monitor the power quality provided by the communication power supply. Therefore, this system detects the power parameters of the communication power supply after an interval of 5 seconds. If the measured data exceeds the warning line range, the alarm information will be sent to the monitoring center. The monitoring center can also modify the detection interval time, alarm range and other parameters at any time. After the communication power supply monitoring point sends the data to the monitoring center via RF radio, the monitoring center will resend the received data to the communication power supply monitoring point. After receiving the data, the monitoring point will start to check whether the sent data is consistent with the received data. If they are the same, it means that the transmission is successful. If they are not the same, the data will be resent. This can ensure the reliability of data transmission.

　　4 Conclusion

　　This paper designs a communication power supply monitoring system based on Web and CC430F6127 single-chip microcomputer. This system has flexible networking and low power consumption. It can timely transmit the conditions of multiple communication power supply monitoring sites to the monitoring center for real-time analysis. The system runs stably and reliably and has great application prospects.

References:

[1]. CC1101 datasheet http://www.dzsc.com/datasheet/CC1101_2035203.html.
[2]. AD7656 datasheet http://www.dzsc.com/datasheet/AD7656_1131528.html.
[3]. DS18B20 datasheet http://www.dzsc.com/datasheet/DS18B20_819975.html.
[4]. 2.0 datasheet http://www.dzsc.com/datasheet/2.0_1758666.html.
[5]. CS8900A datasheet http://www.dzsc.com/datasheet/CS8900A_593567.html.
[6]. SA10 datasheet http://www.dzsc.com/datasheet/SA10_594078.html.