SHT4x — temperature and humidity¶
Being prepared
Chosen for the catalogue; the driver has not shipped yet. The figures below still need checking against the datasheet.
What it does¶
Temperature and humidity, measured properly. Where a cheap sensor is right to within a few percent on a good day, this family is the one to use when the humidity number is going to be acted on — drying, curing, storage, anything where being wrong costs material.
It also has a small heater on board, used to drive moisture off the sensor after it has been sitting in a damp place.
Parameters¶
| Measures | Temperature, relative humidity |
| Temperature range | −40 … 125 °C |
| Humidity range | 0 … 100 %RH |
| Interface | I²C |
Bus and addressing¶
I²C, address 0x44 on the common parts. Some variants are made at a different address so that two can share a bus — check the ordering code.
Wiring¶
Four wires. The sensor opening must see the air it is meant to measure, so it faces out of the enclosure, not into it.
In a project¶
To be written.
Traps¶
| Trap | What to do |
|---|---|
| Reading humidity right after power-up in a damp place | Give it time, or use the heater. A saturated sensor reads high until it dries. |
| Mounting it beside anything warm | Humidity is calculated from temperature. Warm the sensor by a degree and the humidity reading moves several percent. |