Ds18b20 sensorsonde en kabel

The ds18b20 temperature sensor probe has high accuracy. The temperature measurement accuracy can reach 0.01℃, and the temperature measurement accuracy in the wide temperature range is 0.1℃. Good stability and high precision in mass production.

The DS18B20 digital sensor probe and cable are easy to connect and can be used in a variety of situations after being packaged. Such as stainless steel straight pipe type, schroefdraadtype, Type magneetadsorptie, Verschillende modellen, inclusief LTM8877, LTM8874 enzovoort.
DS18B20 is a commonly used digital temperature sensor. It outputs a digital signal and has the characteristics of small size, Lage hardware overhead, strong anti-interference ability and high accuracy. Its appearance mainly changes depending on the application. The encapsulated DS18B20 can be used for cable temperature measurement, blast furnace water circulation temperature measurement, boiler temperature measurement, machine room temperature measurement, agricultural greenhouse temperature measurement, clean room temperature measurement, ammunition depot temperature measurement and other non-limit temperature occasions. Wear-resistant and impact-resistant, small in size, easy to use, with various packaging forms, it is suitable for digital temperature measurement and control of various small space equipment.

Main features of DS18B20 sensor probe
1. Main features of DS18B20
1.1. The adaptable voltage range is wider, voltage range: 3.0~5.5V, and can be powered by the data line in parasitic power mode
1.2. Unique single-wire interface method. When DS18B20 is connected to the microprocessor, it only needs one port line to achieve two-way communication between the microprocessor and DS18B20.
1.3. DS18B20 supports multi-point networking function. Multiple DS18B20 can be connected in parallel on the only three lines to achieve multi-point temperature measurement.
1.4. DS18B20 does not require any external components during use. All sensing components and conversion circuits are integrated into an integrated circuit shaped like a triode.
1.5. Temperature range -55℃～+125℃, accuracy is ±0.5℃ at -10～+85℃
1.6. The programmable resolution is 9~12 bits, and the corresponding resolvable temperatures are 0.5℃, 0.25℃, 0.125℃ and 0.0625℃ respectively, which can achieve high-precision temperature measurement.
1.7. At 9-bit resolution, the temperature can be converted into numbers in up to 93.75ms. At 12-bit resolution, the temperature value can be converted into numbers in up to 750ms, which is faster.
1.8. The measurement results directly output digital temperature signals and are serially transmitted to the CPU via the "één lijnbus". Tegelijkertijd, the CRC check code can be transmitted, which has strong anti-interference and error correction capabilities.
1.9. Negative voltage characteristics: When the polarity of the power supply is reversed, the chip will not be burned due to heat, but it will not work properly.

2. Appearance and internal structure of DS18B20 sensor
The internal structure of the DS18B20 sensor mainly consists of four parts: 64-Bit fotolithografie ROM, temperatuur sensor, non-volatile temperature alarm triggers TH and TL, and configuration register.
The appearance and pin arrangement of DS18B20 are as follows:

DS18B20 pin definition:
(1) DQ is de digitale signaalingang/uitvoeraansluiting;
(2) GND is de krachtige grond;
(3) VDD is the input terminal of the external power supply (Gericht in de parasitaire stroombedradingsmodus).
3. Working principle of DS18B20
The reading and writing timing and temperature measurement principle of DS18B20 are the same as those of DS1820, except that the number of digits of the temperature value obtained is different due to different resolutions, and the delay time during temperature conversion is reduced from 2s to 750ms. The oscillation rate of high temperature coefficient crystal oscillator changes significantly with temperature changes, and the generated signal is used as the pulse input of counter 2. Counter 1 and the temperature register are preset at a base value corresponding to -55°C. Counter 1 counts down the pulse signal generated by the low temperature coefficient crystal oscillator. When the preset value of counter 1 decreases to 0, the value of the temperature register will be increased by 1, the preset value of counter 1 will be reloaded, and counter 1 will restart counting the pulse signals generated by the low temperature coefficient crystal oscillator. This cycle continues until counter 2 counts to 0, then stops accumulating the temperature register value. Op dit moment, the value in the temperature register is the measured temperature. The slope accumulator in Figure 3 is used to compensate and correct the nonlinearity in the temperature measurement process, and its output is used to correct the preset value of counter 1.

ds18b20 sensor with accuracy up to 0.01℃

Aangepaste ds18b20-sensorsonde en kabel

DS18B20 has 4 main data components:
(1) The 64-bit serial number in the photoetched ROM is photoetched before leaving the factory. Het kan worden beschouwd als de adres seriële code van de DS18B20. De opstelling van de 64-bit fotolithografie ROM is: de eerste 8 bits (28H) zijn het producttype nummer, and the next 48 Bits zijn het serienummer van de DS18B20 zelf. The last 8 bits are the cyclic redundancy check code of the previous 56 bits (CRC=X8+X5+X4+1). The function of photolithography ROM is to make each DS18B20 different, zodat meerdere DS18B20's kunnen worden aangesloten op één bus.
(2) De temperatuursensor in DS18B20 kan de temperatuurmeting voltooien. Neem 12-bit conversie als voorbeeld: it is provided in the form of 16-bit sign-extended two's complement reading, uitgedrukt in de vorm van 0,0625 ° C/LSB, waar s het teken is.
Dit zijn de 12-bit gegevens verkregen na 12-bit conversie, die is opgeslagen in twee 8-bit rammen van 18b20. De eerste 5 bits in binary are the sign bits. If the measured temperature is greater than 0, deze 5 Bits zijn 0. Vermenigvuldig de gemeten waarde gewoon door 0.0625 Om de werkelijke temperatuur te krijgen. Als de temperatuur minder is dan 0, deze 5 Bits zijn 1, en de gemeten waarde moet worden omgekeerd, plus 1, en vervolgens vermenigvuldigd door 0.0625 Om de werkelijke temperatuur te krijgen. Bijvoorbeeld, De digitale output van +125 ℃ is 07d0h, De digitale output van +25.0625 ℃ is 0191H, De digitale output van -25.0625 ℃ is FE6FH, en de digitale output van -55 ℃ is FC90H.
(3) DS18B20 temperature sensor memory DS18B20. The internal memory of the temperature sensor includes a high-speed scratchpad RAM and a non-volatile electrically erasable EEPRAM, which stores the high-temperature and low-temperature flip-flops TH, TL en structurele registers.
(4) Configuration register The meaning of each bit of this byte is as follows:
Table 3: Configuration register structure

De onderste vijf bits zijn altijd "1", and TM is the test mode bit, die wordt gebruikt om in te stellen of de DS18B20 zich in de werkmodus of de testmodus bevindt. Dit bit is ingesteld op 0 Wanneer DS18B20 de fabriek verlaat, en gebruikers moeten het niet veranderen. R1 en R0 worden gebruikt om de resolutie in te stellen, Zoals weergegeven in de volgende tabel: (DS18B20 is ingesteld op 12 bits wanneer verzonden vanuit de fabriek)
Table 4: Temperature resolution setting table

4. High-speed temporary storage memory The high-speed temporary storage memory consists of 9 bytes, and its allocation is shown in Table 5. When the temperature conversion command is issued, the converted temperature value is stored in the 0th and 1st bytes of the cache memory in two-byte complement form. The microcontroller can read this data through the single-wire interface. When reading, the low bit is in front and the high bit is in the back. The data format is shown in Table 1. Corresponding temperature calculation: When the sign bit S=0, directly convert the binary bit to decimal; when S=1, first convert the complement to the original code, and then calculate the decimal value. Table 2 shows some of the corresponding temperature values. De negende byte is de redundantiecontrole byte.
Table 5: DS18B20 temporary register distribution

Volgens het communicatieprotocol van DS18B20, the host (single chip microcomputer) must go through three steps to control DS18B20 to complete temperature conversion: DS18B20 moet worden gereset voordat elke lezing en schrijf. After the reset is successful, a ROM command is sent, and finally a RAM command is sent, so that the predetermined operation can be performed on the DS18B20. Reset vereist dat de hoofd -CPU de gegevenslijn naar beneden trekt 500 microseconden en los het vervolgens vrij. When DS18B20 receives the signal, it waits for about 16 naar 60 microseconden, en stuurt dan een lage pols van 60 naar 240 microseconden. De belangrijkste CPU ontvangt dit signaal om een succesvolle reset aan te geven.
Table 6: ROM instruction list