Design of the hottest network air conditioner

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The design of the air conditioner

1 the demand of the air conditioner

in the scorching summer, when you are walking on the way to work, do you want to turn on the air conditioner in the office remotely, so that you can enjoy a cool and comfortable environment when you enter the office? When you leave the office to do business and can't return for the moment, do you want to turn off the air conditioner in the office remotely to save energy? Secondly, in communication engineering, there are many communication workstations in high mountains. These workstations are equipped with expensive communication equipment. In order to make these equipment have a suitable working environment, air conditioners are generally installed in communication workstations. So how can we remotely control the opening and closing of these air conditioners and monitor their operating status? Today, with the development of science and technology, these are no longer dreams. Remote control can be achieved by using air conditioners

2 mode analysis of air conditioner

air conditioner is a brand-new industry. At present, there are many domestic and foreign home appliance manufacturers engaged in air conditioner design and product sales. Their design schemes are different, but they can be summarized into three modes

① control through public dialing. Whether at home or in the engineering computer room, it is accessible. It is very convenient to set up a link through dialing, and then input the remote control command to start up, shut down, adjust the temperature and monitor. The control cost is also very low, especially for the communication station in the mountains

② control through the Internet. Because of the Internet, several songs cover most offices and most families. If you can control them through the Internet, the scope will be wider and more effective, but the cost will be higher. In this control scheme, a web server is built first. When the server is running, remote customers can log in directly. At the same time, a communication subroutine is running in the background of the server. This subroutine sends control commands or receives operation data through rs232/rs485 interface. It can be seen that this scheme has high technical content, but it can transmit a large amount of data

③ controlled by radio communication. In the early days, it was controlled by data transmission of dedicated radio stations, but in the recent years, it is directly controlled by wireless mobile communication (card), and the cost is lower. Because from the control room to the remote workstation, it is almost covered by mobile cells and occupies all the mobile communication resources, which is insignificant for the communication company. The control room and the remote communication station adopt mobile communication, which has reliable links, fast data transmission and low cost. For a longer distance, using satellites as data links is also an optional scheme. First, the satellite transceiver will send the remote control command up to the commercial satellite, and then the satellite will send it down to the remote receiving station, which will decode it and send it to the air conditioner. Then, the air conditioner operates according to the obtained parameters. Or, upload the existing operating parameters to the control room through the satellite link. This scheme requires renting commercial satellites, which may be a little expensive

theoretically, the above three schemes are feasible, but this paper only discusses the first design scheme

3 design of public remote control scheme

for the design of network air conditioner that uses public dialing to control remotely, it is mainly designed according to five modules, which are all crucial

3.1 dial up network link

there are two design schemes

the first scheme is direct dial-up control. This method is especially suitable for the direct control of household air conditioning and office air conditioning by highly mobile personnel. For example, on the way to work, you can dial one, turn on the air conditioner in the office, and set the temperature at 26 ℃ for 5-10 minutes. When you get to the office, you can just enjoy a comfortable environment. Here, dial the destination number first, and then dial the startup command after automatically picking up the phone and getting the voice prompt. Now, generally, dialing is based on the DTMF (dual tone multi frequency) system, and the single audio signal is sent from the machine. The signal is sent to the remote destination through the program-controlled switch. There is a dialing gateway at the destination, which can analyze the dialing characters - in fact, the dialing command, which controls the operation of the air conditioner. There is an audio decoding chip, a single-chip microcomputer control system and rs232/rs485 interface circuit in Guanzhong. A single number is solved through the decoding circuit, and then a complete command is generated through the analysis of the single-chip microcomputer system. Finally, it is sent to the local air conditioner through the RS232 interface and executed by the local air conditioner. This scheme is rough control, and the operating parameters do not need to be returned

the second design scheme is that the computer (PC) controls the remote air conditioner. Many communication workstations are equipped with many expensive transmitters, and the temperature, humidity and other parameters of the workstation need to be returned to the control center for monitoring. In addition, if the running air conditioner fails, the backup air conditioner should be switched immediately to avoid the temperature rise due to the air conditioner failure, which will lead to the failure of other communication equipment. Therefore, it is difficult to use ordinary dialing. Complex control can only be realized by computer (PC). This scheme requires two dial gateways. First, the computer (PC) is connected with the switch through rs232/rs485 interface, and then connected with public dialing. The link from dialing to remote computer is the same as that of the first scheme. When issuing control commands, the computer (PC) dials the destination number first, and the destination switch will respond off hook (no prompt tone). The experimental height of the two switches is greater than 3.5m; The experimental space dispensing hydraulic universal experimental machine adopts the structure of wire rope winding and automatic positioning of electromagnet pin; The pressure loading part adopts the lead screw transmission to successfully establish the link, and then enters the transparent communication. The computer (PC) command is converted into DTMF single tone signal through the first switch. The signal is transmitted to the destination switch through the program-controlled switch, which affects the vertical installation and replacement, and then the DTMF single tone is converted into data flow by the destination switch. The data flow is analyzed into commands from the switch, and sent to the local air conditioner, which operates according to the command; If the operation status and parameters of the air conditioner return, it is a reverse process

the design scheme introduced in this paper is to consider the overall situation and adopt universal design, which can well combine the first scheme and the second scheme, so as to integrate the design of household air-conditioning and engineering air-conditioning, that is, one air switch is suitable for multiple uses. As shown in Figure 1

3.2 design of dial off

dial off is a key module design, which should complete the following four functions

① it can extract DTMF dialing characters 0~9; *; ; (A,B,C,D);

② the extracted characters are connected to the computer (PC) serial port through rs232/rs485 interface

③ automatic off hook after five consecutive rings. If it is an ordinary manual dialing control, a voice prompt will be given after the control is successful, but if it is a computer (PC) dialing control, there will be no voice prompt

④ both uplink and downlink data transmission are adaptive

mc145436 chip is used as the core decoding chip, which completes the decoding from DTMF single tone to four bit binary number. As shown in Figure 2, ain (P7) is the single tone transmission and amplification end. When the decoding is successful, the DV end becomes high, and the single chip microcomputer judges that it is at high level, reads the data from D1 to D4, and sends it out through the serial port; K is the constant point, connected to the ringing circuit, K is the normally open point, connected to the decoding circuit. There is a detection ringing circuit. When ringing, the bridge stack outputs a high level, but the photoelectric coupler outputs a low level in reverse phase. This low level is sent to the p3.2 (into) pin of the single chip microcomputer, causing an external event interrupt. The interrupt program then outputs a high level from the p2.0 pin to make the relay pull in, disconnect the ringing circuit, and connect the normal decoding circuit, so as to automatically pick up and enter the transparent link communication

in this design, AT89C2051 embedded MCU is used as the controller. AT89C2051 is a MCS-51 series compatible MCU produced by ATMEL company. It contains 2K byte EEPROM, 128 byte ram, 15 i/o leads, 2 16 bit timing/counters, 1 five vector two-level interrupt, 1 full duplex serial interface. This chip is selected because of its low cost and sufficient performance and capacity. As shown in Figure 2

if it is ordinary dialing, all characters transmitted are legal characters on the machine, but if it is controlled by a computer (PC), some characters can be extended. As shown in Table 1,

3.3 protocol specification design

whether the system can work harmoniously depends mainly on the support of communication protocol. Sending commands and interpreting commands should follow the protocol specifications, which are divided into ordinary dial-up remote control and computer (PC) dial-up remote control, that is to say, Guan includes two protocols, both of which are interpreted at the same time

① ordinary dial-up control protocol, the command length is as short as possible, and the length is fixed. The format is as follows:

the total length is 5 characters, each character is 8 bits, * is the starting character of the command, # is the end character of the command, area a is the command type, area B and area C are numerical values, usually 00. The actual temperature value is only in the temperature regulation command, as shown in Table 2

② computer (PC) dial-up remote control protocol

in the project site, there are usually various interferences, such as transmitter signal interference, power electromagnetic field interference, etc. in order to prevent misoperation, some special characters can be added to the format of command frame, because computer (PC) can send some special characters and add checksum, Therefore, the format is as follows:

description of the format:

① "55AA" is a two byte hexadecimal number, which is the frame header of a frame command. "55" and "AA" are two related numbers, which are selected for interference. Of course, other numbers can also be taken, and the number with greater correlation is best

② the command length value of this frame is a hexadecimal number of one byte, so it can represent 255 bytes at most, which is enough. Why is the length byte after the frame header? This arrangement is for the convenience of the receiving end, because once the receiving end captures the frame header, followed by the length bytes, the length data is pressed into the counter. After each byte is received, the counter is reduced by one until the counter value is zero one, and the receiving of a frame command ends. Then, the frame data is taken out of the buffer for analysis. It can be seen that it is more convenient

③ uplink and downlink fields: the character "U" indicates that the rogue command is an uplink command, such as the operation status parameter return, and the character "d" indicates that the command is a downlink command, such as power on, power off, etc

④ equipment type segment: this segment is a hexadecimal beacon of one byte, indicating the type of equipment controlled, such as 31 for air conditioning, 32 for refrigerator, 33 for rice cooker, etc

⑤ command type segment: this segment indicates the specific command to be executed. For example, 01 indicates power on, which is the same as the determination of area a in the ordinary dial-up control protocol, but several commands are extended. 09 indicates the increment of temperature - the corresponding data area has +1 and -1 (expressed by complement), indicating that it only increases or decreases 1 ℃ on the original temperature; 10 indicates timing, and the corresponding data area has three bytes. The first byte indicates action, such as 31 indicates timed startup, 32 indicates timed shutdown, etc., and the last two bytes indicate specific time values, with a maximum of 1440 minutes

⑥ the last byte is the parity value. You can also add an answer such as a command according to the actual situation, which is omitted here

3.4 transformation of the original air conditioner

some air conditioners sold in the market are mechanically temperature controlled, some are electronically temperature controlled, and some are

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