ATH10 temperature and humidity measurement is inaccurate

天天1

ATH10 temperature and humidity measurement is inaccurate [Copy link]

 

Currently, an ATH10 temperature and humidity sensor is used to test the temperature and humidity of the board environment. A mechanical thermometer and humidity meter is used for comparison. The current ambient temperature is 18°C and the humidity is 47%. When the device is just powered on, the serial port reads 16°C and 40% humidity. Then the temperature will slowly rise to 17.2°C and the humidity will slowly drop to 39%. The error is relatively large. According to the data in the manual, the temperature difference should not exceed 0.5°C and the humidity should not exceed 4%. For this type of sensor, is the data measured just after power-on the most accurate or the data measured after power-on operation the most accurate? Personally, I feel that the data just after power-on should be the most accurate. After all, running with power later is equivalent to having current interfering with the sensor.

The program tests the temperature and humidity sensor data every 2 seconds.

dcexpert

ATH10, a non-standard I2C, always feels awkward to use.

天天1

dcexpert posted on 2021-2-20 09:35 ATH10, a non-standard I2C, always feels awkward to use.

Why is it called non-standard IIC? Isn't it also two wires?

dcexpert

Tiantian1 posted on 2021-2-20 10:35 Why is it called non-standard IIC? Isn't it also two wires?

I used it a long time ago, and I don't remember it clearly. It seems that it cannot be connected to I2C together with other standard I2C devices.

chunyang

The temperature and humidity sensor in a stable environment for a long time may be relatively accurate in the early stage of power-on, but the reason is not the interference of current as the original poster said, but the temperature rise of the sensor caused by the heating of the system. The reason why it is only "possible" is that if it is true, it means that there is a problem with the design, the location of the sensor in the system is wrong, and it is affected by other heat sources in the circuit.

In most cases, temperature sensors in normal applications should be in a changing environment. Obviously, the measured value after long-term operation should be the most accurate. After all, there is thermal resistance between the sensor and the environment to be measured, and it takes time to reach thermal equilibrium. Only the measured value after thermal equilibrium is accurate.

Mechanical thermometers and hygrometers, i.e. bimetallic thermometers and hair hygrometers, actually have very poor accuracy, and the measured values can only be trusted after being calibrated with reference to a standard table before formal measurement. When making products, the host should use a mercury thermometer as a reference, and a dry-bulb hygrometer based on a mercury thermometer as a hygrometer, and operate strictly in accordance with the specifications. For lower requirements, alcohol thermometers and dry-bulb hygrometers based on alcohol thermometers can be used. The readings of mechanical thermometers and hygrometers that have not been calibrated before use are not credible.

littleshrimp

I couldn't find any information about this chip. I suggest you upload the data sheet.

天天1

littleshrimp posted on 2021-2-21 12:57 I couldn't find the information of this chip. I suggest you upload the data sheet.

Sensor manual uploaded

maychang

"Compared with a mechanical thermometer and hygrometer in my hand, the current ambient temperature is 18°C and the humidity is 47%."

You are using a "mechanical thermometer and hygrometer" as a standard.

The question is: Is this "mechanical thermometer and hygrometer" accurate?

天天1

maychang posted on 2021-2-21 14:56 "Using a mechanical thermometer and hygrometer for comparison, the current ambient temperature is 18℃ and the humidity is 47%" You are using a "mechanical thermometer and hygrometer" ...

Yes, I thought this machine would be very accurate, but I haven't tested it to see if it's actually accurate.

maychang

天天1 posted on 2021-2-21 16:10 maychang posted on 2021-2-21 14:56 "Compared with a mechanical thermometer and hygrometer in my hand, the current ambient temperature is 18℃ and the humidity is 47%." You...

Most physical quantities have international definitions and standards. Each country has its own standards based on international standards. For example, voltage in China is based on the average value of the electromotive force of several (I think it was 24) standard batteries. The Technical Supervision Bureau (formed by the merger of the Bureau of Standards and the Bureau of Metrology) of each province and municipality is a secondary standard, and each district and county is a tertiary standard.

maychang

天天1 posted on 2021-2-21 16:10 maychang posted on 2021-2-21 14:56 "Compared with a mechanical thermometer and hygrometer in my hand, the current ambient temperature is 18℃ and the humidity is 47%." You...

The multimeter you use must have an error level, either marked in the manual or on the dial. According to China's Metrology Law, the multimeter you use should be calibrated regularly by the Technical Supervision Bureau. If the calibration is qualified, it means that your multimeter meets the error level requirements in the manual. The Technical Supervision Bureau has the final say on whether the meter is "accurate".

maychang

天天1 posted on 2021-2-21 16:10 maychang posted on 2021-2-21 14:56 "Compared with a mechanical thermometer and hygrometer in my hand, the current ambient temperature is 18℃ and the humidity is 47%." You...

Of course, the technical supervision bureau of the province or municipality directly under the Central Government has the final say on the standard tools at the county level, and the technical supervision bureau of the province and municipality directly under the Central Government has the final say on the standard tools at the national level.

To determine whether your ATH10 measurement results are accurate, you need to use an instrument that is one level higher than the error in the ATH10 manual and that has been calibrated by the Technical Supervision Bureau.

littleshrimp

Tiantian1 posted on 2021-2-21 13:34 The sensor manual has been uploaded

The thermometer and hygrometer you use for comparison may not be accurate, but the temperature of your device rises slowly after power-on, which is an abnormal phenomenon. One possibility is that the sensor device generates heat due to excessive power consumption. Another possibility is that there is a problem with the PCB layout of your sensor, such as the PCB is not insulated, or there is a problem with the layout of the sensor and the device housing, such as poor ventilation, or close to a heat source.

The PCB layout manual has given an example picture, you can refer to it and try to make the PCB under the sensor independent.

yet

chunyang posted on 2021-2-20 16:15 The temperature and humidity sensors that have been in a stable environment for a long time may indeed be relatively accurate in the early stage of power-on, but the reason is not what the original poster said, that there is current interference, but...

Where to copy and paste

Long-winded answers that don't really matter

chunyang

yet Posted on 2021-2-21 20:55 Where can I copy and paste the long-winded answer that is irrelevant to the question

Then tell me where did you copy and paste from? And where did you answer the question irrelevantly? You are sick!

chunyang

天天1 posted on 2021-2-21 16:10 maychang posted on 2021-2-21 14:56 "Compared with a mechanical thermometer and hygrometer in my hand, the current ambient temperature is 18℃ and the humidity is 47%." You...

Whether it is accurate or not can only be known after calibration with a known accurate meter. If it has never been calibrated, cheap mechanical meters are likely to be inaccurate, especially the hygrometer part. Bimetallic thermometers and hair hygrometers need to be calibrated regularly before the values can be trusted.

okhxyyo

yet Posted on 2021-2-21 20:55 Where can I copy and paste the long-winded answer that is irrelevant to the question

Please read this patiently. This is not a copy and paste.