https://github.com/j0hax/pico-dht
Digital temperature and humidity reporting for the Raspberry Pi Pico
https://github.com/j0hax/pico-dht
dht22 leibniz-university-hannover micropython rpi-pico
Last synced: about 2 months ago
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Digital temperature and humidity reporting for the Raspberry Pi Pico
- Host: GitHub
- URL: https://github.com/j0hax/pico-dht
- Owner: j0hax
- License: gpl-3.0
- Created: 2023-02-13T17:12:21.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2023-03-21T14:10:24.000Z (over 3 years ago)
- Last Synced: 2025-05-11T12:23:40.559Z (about 1 year ago)
- Topics: dht22, leibniz-university-hannover, micropython, rpi-pico
- Language: OpenSCAD
- Homepage:
- Size: 3.61 MB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# pico-dht
Digital temperature and humidity reporting for the Raspberry Pi Pico, used to continuously monitor a server room at the Mechanical Engineering Campus of Leibniz University Hannover.
## Hardware Used
1. Raspberry Pi Pico
2. DHT22/AM2302 or DHT11 sensor
3. Wires/Breadboard
4. 3D-printed case (optional)
### Wiring
| Pi Pico Label | Purpose | DHT22 Pin |
|---------------|---------|-----------|
| 3V3 | Power | 1 |
| GPIO 15 | Data | 2 |
| GND | Ground | 4 |
### Notes
- Many variants of the DHT22/DHT11 will have four pins. The third pin is unused.
- A pull-up resistor can be used but is not required, as the DHT22 has its own built-in.
## Install
By copying `main.py` to the Pico's on-board flash memory, it is executed at every boot.
Standard DHT drivers were [migrated](https://github.com/micropython/micropython/pull/9220) to `micropython-lib` starting with MicroPython 1.19, so most tutorials on the internet regarding this sensor no longer work!
The [dht](https://github.com/micropython/micropython-lib/blob/master/micropython/drivers/sensor/dht/dht.py) package can be copied over serial or installed OTA by modifying and executing `setup.py` on an internet-connected Pi Pico W. The library is should be saved to internal flash at `/lib`.
## Usage
A periodic timer is set to request sensor data every 3 seconds. The values are JSON encoded and printed over serial.[^1] The onboard LED will be on for the duration of this subroutine.
On most Linux hosts, the Pi Pico will be available under `/dev/ttyACM0`. The reading processes may need to part of the `dialout` group.
For an example implementation to read this data, see [dht22-nagios](https://github.com/j0hax/dht22-nagios).
### Connection Errors
If the wires are not soldered and knocked around, a connection may become flaky and a GPIO error can occur. Any errors when reading data are reported in the JSON's `error` attribute as a POSIX errno.
## Case
The 3D-Printed case can be used to mount the internals. It features a hook to hang the arrangement from the ceiling.
[OpenSCAD](https://openscad.org/) is used to model, customize and compile the final STL.
[^1]: Unfortunately, WPA2-EAP Networks such as eduroam are not supported very well by MicroPython at the moment.