Per the data sheet, the status bits (least significant 2 bits of measurement value) should be set to 0 before calculating physical values.

This is mentioned in the third paragraph on page 12 and in the first paragraph of the "conversion of signal outputs" section on page 15.

It appears to me that the measurement value is used as read without clearing the status bits.

Apparently the bits only need to be cleared (not removed from the measurement value) and the conversion formulas take this into account.

Larry

There is no need to wait if something is available after Wire.requestFrom().
When the Wire.requestFrom() returns, the I2C transmission has completely finished. The Wire.available() returns the number of bytes in the buffer.

The return value of Wire.requestFrom() could be checked if three bytes are received. Both "while (!Wire.available()) {}" can be removed.

Hi,
i use multiple humidity sensors all with according adafruit libraries. Obviously HTU21D gives odd values sometimes up to 110%. This graphs shows the values without additional computing.

The new version of the library (1.0.1) does not work with my Si7021 . Whereas 1.0.0 works without problems.

Problem in method ::begin
`
boolean Adafruit_HTU21DF::begin(void) {
Wire.begin();

reset();

Wire.beginTransmission(HTU21DF_I2CADDR);
Wire.write(HTU21DF_READREG);
/* Wire.endTransmission();
Wire.requestFrom(HTU21DF_I2CADDR, 1);
Serial.println(Wire.read(), HEX);
return (Wire.read() == 0x2); // after reset should be 0x2
*/
return (Wire.endTransmission() == 0);
}
return (Wire.read() == 0x2); // after reset should be 0x2 instead of 0x2 returned0x3A

I slightly corrected the code as shown above - so everything is OK!

The example looks OK after implementing issue #3 but in my first test it crashes after a few readings.
I need to hard reset to get it working again.
I'm using the nightly build version 1.6.4-835-g77d77e8 from github.com/esp8266/arduino with the Arduino board installer

r��HTU21D-F test
Temp: 24.97 Hum: 56.76
Temp: 41.01 Hum: 56.73
Temp: 24.97 Hum: 56.75
Temp: 24.98 Hum: 56.69
Temp: 24.97 Hum: 56.63
Temp: 24.97 Hum: 56.60
Temp: 24.95 Hum: 56.54
Temp: 24.98 Hum: 57.45
Temp: 25.00 Hum: 57.35
Temp: 24.98 Hum: 57.18
Temp: 24.98 Hum: 57.08
Temp: 24.99 Hum: 56.94
Temp: 24.98 Hum: 56.88
Temp:
ctx: cont
sp: 3ffe9b60 end: 3ffe9d40 offset: 01b0

stack>>>
3ffe9d10: 40201c75 3ffe8bf0 3ffe9d98 40202158
3ffe9d20: 00000000 00000000 3ffe9d64 40201cce
3ffe9d30: 00000000 00000000 3ffe8d20 40100118
<<<stack<<<

ets Jan 8 2013,rst cause:1, boot mode:(1,7)

ets Jan 8 2013,rst cause:4, boot mode:(1,7)

wdt reset

Hey Guys,

Your librarys are allways great and I like working with products of yours. However, I bet you know from the title where this is going. I haven't checked, but please take a look over your libraries, one can easily miss this issue, but it's easy to fix ;)

For the sake of completeness:

• Arduino board: Arudino DUE
• Arduino IDE version (found in Arduino -> About Arduino menu): 1.8.4
• List the steps to reproduce the problem below (if possible attach a sketch or
  copy the sketch code in too): Include the library twice. Done. Compiler crashes. See ironic.txt for a sketch.

Please include something of the following style in your code:
#pragma once
or

#ifndef __ADAFRUIT_HTU21DF__ 
#define __ADAFRUIT_HTU21DF__ 

// header code goes here

#endif

https://forums.adafruit.com/viewtopic.php?f=19&t=78770

Arduino board: NODEMCU 0.9 esp8266-12 (non E)

Arduino IDE version 1.6.12

• loaded the example and it just crashes, the SparkFun lib works fine so think there's an internal compatibility issue on this one

To avoid any kind of problem with non- AVR boards, please tag the library's HEAD in order to include 23176b9

Thanks 😄

• Arduino board: NODEMCU 0.9 esp8266-12 (non E)

• Arduino IDE version 1.6.12

• this library is not the one that is loaded by 'add libraries' in the ide - it loads an older one or the versioning is wrong.

Hi ,
while reading the data from the HTU21D-F the for both temperature and humidity the first byte is OK , but the second and third bytes are "0xFF"