Issues with widely out readings

[mitra42]

I'm seeing problems with consistently wrong readings and not sure if I'm doing something wrong or what.

My setup is a D1 mini (early version) connected to a KY-015 which is supposed to be a DHT11
https://arduinomodules.info/ky-015-temperature-humidity-sensor-module/
I've got it hooked to 5V but get the same results at 3.3V

I'm currently hooked up to pin D2 but I get the same results on pin D1

I couldn't find a canonical - simplest possible - example - so I'm using "array". The unconnected sensors just show 999's as I'd expect but the D2 is showing ...
20:48:04.094 -> 1, Waiting for read, 2048.5, 537.8, 4, 22
Which I take as a humidity of 2048% and temperature of 537C, and that the device is actually a DHT22

It seems consistent - I've tried some of the other examples and get similar results.

If I breath on the sensor, as expected temperature and humidity go up.

[mitra42]

Full disclosure .... at some point I had the pinout wrong (order is data; V; Gnd on the KY-015). Its possible I've damaged the sensor, but then I'd expect to get no readings rather than strange ones). Unfortunately I don't have another of these devices to swap with.

[RobTillaart]

Thanks for reporting this,

It might be that the KY-015 is not 100% compatible too.
Did you compare the datasheets?
Or do you have a link to the datasheet of the KY-015?

[RobTillaart]

The link shows some code which is very opportunistic in the timing. They hardcode delays where I know from experience that there is some spread in the timing if you compare actual sensors.
That said the code looks indeed DHT11 alike.

Can you run the dhtnew_pulse_diag_ext.ino sketch and post its output?

[RobTillaart]

Its possible I've damaged the sensor, but then I'd expect to get no readings rather than strange ones).

mmm, anything is possible, the internal processor might still work but the "physics" part might be fried.

[mitra42]

Thanks Rob
I couldn't see how I did something so stupid, but the problem was there are incorrect pinouts online https://www.thegeekpub.com/wiki/sensor-wiki-ky-015-dht11-combination-temperature-and-humidity-sensor for example has them wrong in first two images, correct in the bottom two - and since of the tutorial writers copy each other its not the only place.

https://oshwlab.com/adrirobot/ky-015-temperature-and-humidity-sensor-module has the correct circuit diagram - dead simple, just one pull-up on the data line.

The board comes from a cheap collection of all the Arduino sensors on AliExpress, no data sheet or confirmation - it is specified as being KY-015 but I can't see how to tell as visually the DHT11 and DHT22 look the same (mine is blue, but they both appear to come in both colors).

I thought it was a decimal point issue, but current figures from the DHT are 2407.1, 487.2, while my SHT is reporting 75% and 24C

Will add output of dhtnew_pulse_diag_ext.ino to next comment.

(Minor suggestion: rename one of the examples as something like dhtnew_simple, it was hard to figure out which was a standard example to copy from and which were, like this, your tests. )

[mitra42]

07:46:25.634 -> dhtnew_pulse_diag_ext.ino
07:46:25.634 -> 
07:46:25.634 -> 
07:46:25.634 -> ===================================
07:46:25.634 -> awake 2 3 4 11
07:46:25.685 -> 10
07:46:25.685 -> 9
07:46:25.685 -> 8
07:46:25.685 -> 7
07:46:25.685 -> 6
07:46:25.685 -> 5
07:46:25.685 -> 4
07:46:25.685 -> 3
07:46:25.685 -> 2
07:46:25.685 -> 1
07:46:25.685 -> 5 6 7 
07:46:25.685 -> 
07:46:25.685 -> RUN:	1
07:46:25.685 -> IDX:	89
07:46:25.685 -> WAKEUP
07:46:25.685 -> 	1125	14	13	29	18	9
07:46:25.685 -> HUM
07:46:25.685 -> 	47	27	48	27	52	26	53	75	52	79	54	25	52	27	52	26
07:46:25.685 -> 	53	75	54	25	53	76	52	26	53	29	52	27	52	26	53	26
07:46:25.685 -> RAW H:	0b1100010100000 = 0x18A0 = 6304 = 630.4%
07:46:25.685 -> 
07:46:25.685 -> TEMP
07:46:25.685 -> 	53	26	53	26	52	76	52	26	53	30	52	25	54	75	52	75
07:46:25.685 -> 	54	75	53	26	52	75	54	75	53	25	53	7221	1	12	1	11
07:46:25.685 -> RAW T:	0b10001110110100 = 0x23B4 = 9140 = 914.0C
07:46:25.685 -> 
07:46:25.685 -> CRC
07:46:25.685 -> 	1	10	1	11	1	10	1	11
07:46:25.685 -> 	1	10	2	10	1	11	1	14
07:46:25.685 -> CRC:	0b0 = 0 <=> 143
07:46:25.685 -> 
07:46:25.685 -> 
07:46:25.685 -> BYE
07:46:25.685 -> 	10	5
07:46:25.685 ->
07:46:30.669 -> 
07:46:30.669 -> ===================================
07:46:30.669 -> awake 2 3 4 5 6 7 
07:46:30.669 -> 
07:46:30.669 -> RUN:	2
07:46:30.669 -> IDX:	89
07:46:30.669 -> WAKEUP
07:46:30.669 -> 	1113	2	19	81	84	5
07:46:30.669 -> HUM
07:46:30.669 -> 	48	25	54	75	52	27	52	75	54	75	52	26	53	75	54	77
07:46:30.669 -> 	54	25	54	25	52	27	52	27	52	26	53	26	53	75	53	78
07:46:30.669 -> RAW H:	0b101101100000011 = 0x5B03 = 23299 = 2329.9%
07:46:30.669 -> 
07:46:30.669 -> TEMP
07:46:30.669 -> 	53	26	52	27	52	26	53	76	52	27	52	75	53	26	53	28
07:46:30.669 -> 	54	25	54	25	53	26	52	27	52	26	53	75	54	25	53	30
07:46:30.669 -> RAW T:	0b1010000000100 = 0x1404 = 5124 = 512.4C
07:46:30.669 -> 
07:46:30.669 -> CRC
07:46:30.669 -> 	52	25	54	75	52	75	54	75
07:46:30.669 -> 	52	27	52	75	53	76	52	30
07:46:30.669 -> CRC:	0b1110110 = 118 <=> 118
07:46:30.669 -> 
07:46:30.669 -> 
07:46:30.669 -> BYE

[mitra42]

Only change I made to the sketch was to set the pin D2, and serial speed, and note that its a ESP8266, not an ESP32.

uint8_t   _dataPin = D2;

Serial.begin(460800); delay(5000);

[RobTillaart]

Thanks for the log data. Will look at it tomorrow as it is rather late here.

The DHT11 is often blue and the DHT22 light gray,

[mitra42]

Out of curiousity .....
I tried the simple sketch from here https://arduinomodules.info/ky-015-temperature-humidity-sensor-module/ on the same device.
It reported Humdity = 94.4%; Temperature = 20.6C
also interestingly - and repeatably - checksum readings were wrong on the first few readings, then switched to OK, though the output didn't change.

And my temp/humidity (cheap consumer) device is reporting 79% humidity 21C which is close to the SHT.

I've also tried switching voltage (3.3V vs 5V); switching to a newer version of the D1 Mini; and switching which data pin. Whichever sketch I'm using the results stay consistent with those changes.

[mitra42]

My DHT is blue.

[RobTillaart]

Had a quick look and the decoding could be...

Humidity is 5B03 that could be integer byte and a decimal byte. Makes 91.3% Hum.

Temperature is 0x1404 => 20.4C

To be continued...

[RobTillaart]

That matches the info in the link and gives something to work with.