Design scheme of the hottest temperature measureme

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Design scheme of temperature measurement and control system

because there are many kinds of wireless transceiver modules at present, how to select the required modules in the design is very critical. The correct selection can reduce detours, reduce costs, and promote products to the market faster. The new wireless transceiver module ZF introduced in this paper is a kind of ultra-small, ultra-low power consumption, high-speed wireless data transmission module. It adopts serial port transmission, with very simple application and programming, high transmission efficiency, less peripheral components, low product development cost, low power consumption, fewer pins and small packaging, which is conducive to reducing PCB area and cost

The development of ZF power battery is a process from short supply to oversupply. 6 it is composed of a single IC. It adopts FSK modulation and combines reception and transmission, so it has strong anti-interference ability; It is suitable for embedded devices. It adopts low transmission power and high sensitivity design, which can meet the requirements of wireless regulation without using a license. It is an ideal choice for low-power wireless data transmission at present. The main characteristics of ZF are as follows:

● integration of reception and transmission

● the working frequency is the international 433MHz data transmission frequency band

● FSK modulation mode is adopted, which has strong anti-interference ability, especially suitable for industrial control occasions

● frequency synthesis technology is adopted, with excellent frequency stability

● sensitivity up to - 118dbm

● the maximum transmission power is + 10dBm

● low working voltage (3.3v~5v), low power consumption

● the highest working rate can be 1200/2400/4800/9600/19200bps

● small volume exceeding the heat treatment system in Table 1

● it can be directly connected to the serial port of single chip microcomputer, which is very convenient for programming

● due to the design of low transmitting power and high receiving sensitivity, there is no need to apply for a license when using

zf pin function

zf module pin diagram is shown in Figure 1. The functions of each pin are as follows:

GND: power ground

vcc: positive power supply 3.3v~5v

rxd: TTL data receiving end

txd: TTL data sending end

sgnd: signal ground

d+ (TXD): RS-232 data sending end/rs-485d+

d- (RXD): RS-232 data receiving end/rs-485d-

zf application in temperature measurement and control system

ZF can realize point-to-point transmission of data acquisition, and can also form a point-to-multipoint bidirectional data transmission channel

in this system, ZF can transmit the temperature data collected by the temperature sensor to the computer and the control signal sent by the computer to the single chip microcomputer, so as to realize the wireless data communication between the single chip microcomputer and the computer. ZF can be directly connected to the serial port or i/o port of MCU. When connecting, RXD at the receiving end of ZF wireless module should be connected to the sending end of MCU serial port, and TXD at the transmitting end should be connected to the receiving end of MCU serial port. Using the i/o of single chip microcomputer, the emission, channel conversion and low power consumption mode of the module can be controlled

based on the characteristics of wireless transceiver module, special attention should be paid to the formulation of communication protocol and the processing of error correction and detection when designing the software of the system. When there is no signal, the serial output of ZF is random data, so the first thing of the protocol is to be able to identify noise and valid data. Through tests and experiments, it is found that oxff followed by oxoo is not easy to occur in noise. Therefore, the single extruder originated in the 18th century. The sending data of the tablet machine can start with the byte of any content (because the data of the first byte is easy to be lost when sending), and then oxff followed by an ooxoo. The receiving protocol stipulates that the receiving only starts with oxff. And followed by an oxoo packet

in addition, attention should be paid to the correction and error detection of data. The error detection of this system adopts the method of checksum square and then formula. The error correction adopts the method of continuous transmission for three times. The same data is sent three times continuously, and then each bit of the three data is compared at the receiving end. If the bit of at least two data is the same, then the bit is correct. In short, A complete wireless transmission protocol is:

[start 1 [start 1 [start 2 [data 1 [data 2 [data 3 [checksum.

where the first one is oxff and the second one is oxoo. If the checksum is correct, it means that the data transmission is complete. Then compare data 1, data 2 and data 3, and take two of the same ones to give a response signal. If the data transmission itself is incomplete, it will not respond, and the system will resend the data.

because the system composed of ZF can complete point-to-point data acquisition and transmission and point to multipoint bidirectional data transmission, ZF It can be widely used in remote control, telemetry, wireless meter reading, access control system, community paging, wireless tag, identity recognition, contactless RF smart card, security system, wireless remote control system, biological signal acquisition, hydrometeorological monitoring, electronic station board, intelligent transportation, wireless electronic scale, industrial equipment data acquisition, and various measurement and control equipment

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