On 14 Jul 2023 10:53, Joe wrote:
On Fri, 14 Jul 2023 09:27:12 +0200
Bruno Kleinert <fu...@debian.org> wrote:
Hello,
I'm looking for a wireless way to measure temperature and humidity
indoor with hardware off the shelf and software included in Debian 12
bookworm.
Sensors --> Radio --> Receiver --> Any typical PC interface, e.g.,
USB, Ethernet.
I don't need a visual interface, but plan to process measured values
in shell scripts.
Do you have any hardware recommendations and can you share experience?
I use DS18B20 chips (1-wire protocol, nice for long distances cabling)
and some BME280s or MPL3115A2, plugged on Raspberry Pies.
The DS18B20 can be directly manipulated via sysfs, while the BMEs and
the MPL3115A2 need a software library to interpret the sensors output (I
use Adafruit's one, in python).
A cron script records the values in a CSV, which I've linked in the
apache folder so remote hosts can access the data file (trying to
display a graph from 5 sensors values on a full year time period is a no
go on a Raspi B v3).
I've also created 2 webpages, one to quickly display the last X values
(tail -n X), one to display a pretty graph, depending on some web form
parameters (source host, from day X to Y, last week, etc).
I'm using jpgraph, a PHP graph lib (free for personal use), to display
nice curves.
If you're not a web dev, you could also use OoO Calc or Excel to build
the graphs from the CSV files.
As you want wireless, I'd recommend a Raspi zero as it has BT+wifi
built-in, a clock (kind of), an IP stack, a webserver, etc.
Of course an Arduino is simpler, but requires a bit more work (and maybe
money) : no built-in storage, no built-in comms, no date/time. But ok,
you don't need local storage or a clock/time if only sending values to
another host, the remote host can set the time before recording.
Although if you operate on batteries, an Arduino would be the best
choice, as it requires a lot less energy.
Another choice could be a Raspberry Pi Pico, but that's closest to an
Arduino than to a Raspi (ie. no OS). But if I'm not mistaken, the
advantage of the Pico is that it has built-in BT+wifi (I've not tested
it, only read about it).
In all cases, you could also turn the wireless chip(s) off till not
sending data, or even go to (deep) sleep mode between polls (IIRC
Arduino/Pico only).
and a bit of PHP to make a 7-day graph web page of T and H. Boot script
to set up the serial port and initiate logging on reboot.
Joe, out of curiosity, what are you using to display the graphs ?
If you didn't read above, I'm using jpgraph, a PHP lib.
