TinuDHT is a C library for working with the DHT11 temperature/humidity sensor intended to be used with the Tinusaur but should also work with any other board based on ATtiny85 or similar microcontroller.
There are of course may libraries (sometime called drivers) to work with DHT11 and the more advanced DHT21/DHT22 but they were written primarily for the Arduino environment and do not work well (or at all) with pure ATtiny boards.
The DHT11 is very basic, low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor for measurements, and sends out the info to the data pin. It is relatively simple to use it, but requires precise timing to retrieve the data correctly. One disadvantage of this sensor is that you can get new data from it no more often than once every 1 or 2 seconds.
The primary problem with the direct use of the Arduino libraries is that the ATtiny85 and Tinusaur in particular do not have enough resource to handle the send/receive process properly, i.e. not enough CPU power, in result of which the timing of the signals that are sent to the sensor and received from it become messed up. In addition those libraries use Arduino specific code and/or C++ specific syntax which makes them incompatible with the plain C language.
This library is based on DHT11Lib code. It was adapted for ATtiny, removed Arduino dependencies and timing was adjusted to work well on ATtiny85 at 1 MHz. There are few other changes and optimizations for speed and size.
TinuDHT is written in plain C and does not require any additional libraries to function except those that come with the WinAVR SDK.
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