Traditional mercury or alcohol thermometers have relatively single functions, long measurement times, inconvenient readings, and long measurement times. In the digital age, traditional temperature measurement tools are no longer able to meet the requirements of design. The following introduces a digital temperature with I2C communication interfacesensorSD5075 is used to implement temperature measurement function, and its software and hardware design scheme is explained in detail. The temperature resolution of this temperature measurement device is 0.1 ℃, and the temperature measurement accuracy is within the range of -40 ℃ to+100 ℃, with a typical error of less than ± 0.5 ℃.

System composition:

The entire system consists of digital temperature sensors, microcontrollers, displays, buttons, and power supplies.

SD5075Delay threshold register and over temperature threshold register can be set. If actually testedenvironmentIf the temperature exceeds the set over temperature threshold, the register outputs an alarm signal through the open drain pin ALARM. If the actual ambient temperature is lower than the hysteresis threshold register, the alarm signal will be released. There are two optional working modes for Alarm output: Alarm comparator mode and Alarm interrupt mode. The alarm output can be selected to be active at high or low levels. The detailed operation process can refer to SDIC's SD5075 single bus digital temperature sensor specification book.

SD5075Introduction:

SD5075It is a high-precision temperature sensor chip that contains a high-precision temperature measurement ADC. The typical error is less than ± 0.5 ℃ in the range of -40 ℃~+100 ℃, and less than ± 1.0 ℃ in the range of -55 ℃~+125 ℃. It is easy to establish communication with other devices through a two-wire I2C/SMBus interface. Set the address lines A2~A0, which can support parallel bus connection of 8 chips.

This chip can operate in three modes: continuous temperature measurement mode, single temperature measurement mode, and shutdown mode. Flexible selection and configuration based on speed or power consumption requirements.

SD5075Features:

112 digit temperature reading with a resolution of 0.0625 ℃.

2The maximum error is ± 0.8 ℃ within the range of -40 ℃ to+100 ℃, and ± 1.5 ℃ within the range of -55 ℃ to+125 ℃.

32-wire communication interface, compatible with I2C/SMBUS protocol.

4Provide over temperature alarm function, which can set over temperature threshold and hysteresis recovery threshold.

5Optional continuous temperature measurement mode or single temperature measurement mode.

6Low power consumption: The typical working current during continuous temperature measurement is only 170uA, and the working current in shutdown mode is less than 1uA

7Operating voltage range: 2.7V to 5.5V

8Pin compatible with ADT75/LM7/TMP75

SD5075Pin description:

SDATwo line communication data cable

SCLTwo line communication clock line

ALARMUsed for temperature alarm or SMBus Alert

GND: Ground

A2-A0Address selection signal

VDD: Power supply

microcontroller

The microcontroller model used is SD8102, which was also developed by Hangzhou Jinghua Microelectronics. Featuring 16k bytes OTP space, 256 bytes SRAM, 19 programmable I/O ports, 3 16 bit timing/counters, and a built-in 2M RC oscillator. This microcontroller can also be replaced by a regular 51 microcontroller or PIC microcontroller.

Display, buttons, and power supply

Using a 5-digit digital display, retaining 1 decimal place, the output method adopts dynamic scanning form, selecting 5 I/O ports of the microcontroller as the bit lines of the digital display and 8 I/O ports as the segment lines of the digital display;

Switch between Celsius and Fahrenheit displays using the S0 button.

Using an external power supply (no current limiting resistor is required for 5-12V, and a current limiting resistor of 470R/3W is added for voltages greater than 12V), the system modules are powered by HT7533 voltage reduction to 3.3V.

The temperature measurement chip used in this temperature measurement scheme has the characteristics of low energy consumption, high temperature measurement accuracy, and low price. Suitable for ordinary temperature measurement occasions and compatible with multiple temperature measurement chips.