---
name: "dht22"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/dht11"
---

# dht22(4)

driver for DHTxx and AM320x temperature and humidity sensors

Part of [dht11(4)](/dht11/4.md).

## NAME

**gpioths** – driver for DHTxx and AM320x temperature and humidity sensors

## SYNOPSIS

To compile this driver into the kernel, place the following line in your kernel configuration file:

**device gpioths**

Alternatively, to load the driver as a module at boot time, place the following line in [loader.conf(5)](/loader.conf/5.md):

```
gpioths_load="YES"
```

## DESCRIPTION

The **gpioths** driver supports the DHTxx and AM320x family of temperature and humidity sensors. The driver automatically reads the values from the sensor once every 5 seconds, and makes the results available via [sysctl(8)](/sysctl/8.md) variables.

## HARDWARE

The **gpioths** driver provides support for the following devices:

| | |
| --- | --- |
| DHT11 | DHT12 |
| DHT21 | DHT22 |
| AM3201 | AM3202 |

The supported devices are all similar to each other, varying primarily in accuracy and resolution. The devices require a single wire for data communications, using a custom protocol which is not compatible with Maxim's 1-wire(tm). The AM320x devices also support connection to an i2c bus, but this driver supports only the single-wire connection option.

## SYSCTL VARIABLES

Sysctl variables are used to access the most recent temperature and humidity measurements.

- *dev.gpioths.\<unit\>.temperature*

  The current temperature in integer deciKelvins. Note that [sysctl(8)](/sysctl/8.md) will convert those units to display in decimal degrees Celsius.

- *dev.gpioths.\<unit\>.humidity*

  The current relative humidity, as an integer percentage.

- *dev.gpioths.\<unit\>.fails*

  The number of failed attempts to communicate with the sensor since the last good access. Cleared whenever a set of measurements is successfully retrieved.

## FDT CONFIGURATION

On an [fdt(4)](/fdt/4.md) based system, a **gpioths** device node is typically defined directly under the root node, or under a simplebus node that represents a collection of devices on a board.

The following properties are required in the **gpioths** device subnode:

- *compatible*

  Must be "dht11".

- *gpios*

  A reference to the gpio device and pin for data communications.

### Example of adding a sensor with an overlay

```
/dts-v1/;
/plugin/;
#include <dt-bindings/gpio/gpio.h>
/ {
    compatible = "wand,imx6q-wandboard";
};
&{/} {
    dht0 {
        compatible = "dht11";
        gpios = <&gpio5 15 GPIO_ACTIVE_HIGH>;
    };
};
```

## HINTS CONFIGURATION

On a [device.hints(5)](/device.hints/5.md) based system, such as MIPS, these values are configurable for **gpioths**:

- *hint.gpioths.\<unit\>.at*

  The [gpiobus(4)](/gpiobus/4.md) instance the **gpioths** instance is attached to.

- *hint.gpioths.pins*

  A bitmask with a single bit set to indicate which gpio pin on the [gpiobus(4)](/gpiobus/4.md) to use for data communications.

## SEE ALSO

[fdt(4)](/fdt/4.md), [gpiobus(4)](/gpiobus/4.md), [sysctl(8)](/sysctl/8.md)

## HISTORY

The **gpioths** driver first appeared in FreeBSD 11.1.