HTU21D Humidity / Temperature Sensor

PhilHornby

Senior Member
I have recently started to investigate the HTU21D Humidity / Temperature Sensor - having found them on eBay for only £1.90 each. (That is, mounted on a PCB with SDA/SCL pull-up resistors, but no regulator - so strictly 3V only). At that price, they are cheaper than DS18B20's (which of course, only measure temperature, are less accurate and take longer to take a reading).

Building on the information already in the forum, I wrote some Demo / Testing code to put them through their paces, should anyone be interested.

http://www.picaxeforum.co.uk/showthread.php?29789-Demonstration-Test-program-for-HTU21D-Humidity-Temperature-sensor
 

PhilHornby

Senior Member
Si7021 vs HTU21D

It's the Sparkfun design, complete with their logo on the board and their description. See:
https://www.sparkfun.com/products/13763

They have a hookup guide with sample code and a library.
It's a very similar board, populated with the very similar Si7021. (The Si7021 has one or two extra features over the HTU21D - though nothing actually useful! (Heater power settings + firmware revision level))

Sparkfun's code is fairly minimalist and is in C++/Wiring for the Arduino .
 
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