What should I use instead of dht22?

Projects General Guidance
1

Hello.
I am working on egg incubator and I was using dht 22 sensor but I had some problems with it.

Temperature readings every couple of minutes were false (lower or higher for up to 3 degrees Celsious).

So I am looking for new humidity and temperature sensor. I would like temperature accuracy +/-0.5 degrees Celsious and humidity can be in range +/- 5%. And I dont find any sensor module which doesent use I2C, (because I am using I2C LCD) so I need for some help finding right sensor.
I was looking at Si7021 or even bme280 but they all use I2C (or at least these I found).. so I want to find something that uses normal analog or digital input..
I still can connect LCD without I2c module but Its really a lot easier to connect it with I2c module so if I dont find any sensor without I2c I will just connect lcd without I2c module..

Thanks

2

You do know that multiple devices can live happily together on the I2C bus, right?

So why the struggle to avoid I2C?

a7

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3

Hmm, I didnt know that.. I was reading some forums and I thought that you cant use multiple devices on same I2C.

So LCD and temp./hum. sensor would work together?

4

Haha, read better fora!

With a few noted exceptions, I2C is a bus and many can catch a ride in it.

In rare occasions there can be an address conflict.

You might want to have handy a sketch called an I2C scanner:

Hook up one device at a time and confirm it shows up at its fixed address, or the address you set on devices that afford that ability.

a7

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5

So devices just need have diffrent addresses? and you connect both devices on sda and scl pins?

6

Correct.

There must also be pullup resistors on the lines.

If you supply the make and model of the devices you intend to connect, it can be determined if anything besides hooking them up needs be done.

Maybe you'd need to add resistors, maybe you'd need to remove them from one or more devices.

Not a real problem.

a7

1 Like
7

Ok, I understand now.

So back to sensors.. Does anyone know for accurate temperature and humidity sensor (module), with temperature accuracy +/- 0.5°C and humidity accuracy around +/- 5% or even better?

I can google it but I mean from your experiences if you know for good sensor and probably from aliexpress :sweat_smile:

8

Perhaps your problem is related to the fact that the DHT22 is not an I2C device.

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9

Shall we read all the datasheets and give the answer to you?

Do it for your self.

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10

I know that it isnt, but DHT 22 is working weird.. It has drops in reading temperature for like 3 degrees Celsious.

11

Sorry, I didnt mean anything rude.. I just wanted to ask if anyone has experience with any accurate sensor. I will of course find it myself.

12

have a look at the BME280 which is an I2C device
there are a number of Arduino libraries with support it, e.g. https://github.com/BoschSensortec/BME280_driver, Adafruit BME280
if you require higher accuracy, stability, etc you will have go to commercial/industrial sensors

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13

Thank you :wink:

14

If you order BME280, mdke sure that it is BME280. There are also BMP280 devices being sold. The BMP280 does not measure humidity.

Is temperature only what you wish to measure? Or are you also interested in humidity?

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15

Thank you for reminder.

No, I need to measure temperature and humidity. (I just need accurate temperature, humidity its also important but not as temperature)

I was looking at sensors on aliexpress. What do you think about this one AHT 21

16

I use this line of products:
STH1x.
They are "professionals".

Datasheet_SHT1x_V4.0_C1.pdf (326.6 KB)

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17

Are you sure its a sensor issue?
The issue could be in your code or wiring, which you can see but we can't.

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18

Oh, thank you. I saw them too when I was looking at sensors.. I will take a closer look at it.

19

Yes, I am pretty sure. I have DHT 22 module so I just connect 5V, GND and output. I used adafruit and other libraries but at some time even if it is in closed room like under box or something it gives normal temperature readings but then like 5 readings are weird.. +/- about 3 degrees Celsious and sometimes it can be very disturbing.. It is possible that it doesent work correctly because once my arduino burned out and DHT was connected to it..

20

I think I've seen your user name around here before. You must know, wiring diagram and sketch is required. That is really a basic need.

If you have some kind of apparatus that is involved with the readings, it would behoove you to post information about that as well.

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