A temperature monitor based on and ESP32 and DS18B20 sensors, that can be mounted in a server rack.
I know, yet another temperature monitor ... This is my first complete project that involves CAD design, 3D printing, electronics prototyping, C code (I am not a developer ;) and webhooks.
Goals of this project :
- Getting temperatures from the 3 sensors (AC, back of the server racks and ambient)
- Log the temperatures and build a graph to monitor trends overtime.
- Send live alerts when a temperature level is reached.
I initially prototyped the temperature monitor using the typical breadboard :
I spliced the sensors to Cat5 network cables and ended cables with mini-XLR connectors (these are pretty cool as they have 3 pins and a locking lever). The DS18B20 is accessed through a one wire bus, it means that they are all connected to the same wire and you can add many sensors as long as you power them accordingly.
I used a old epson ribbon printer cartridge as a case for 3 female plugs. These are connected to the main wire going to the controller. I could easily go with many other sensors plugging in one of these plugs ...
Each sensor has an address and you can use the code from the DS18B20 Sensor Address.c sketch to figure them out. Upload the sketch to the esp32, plug one of the sensor, switch on, read the value in the serial monitor, switch off, plug another sensor, ...
Label your sensors in case you want to move them or reuse them.
The first interation of the case revealed that wifi does not do well when the antenna of the controller is placed between 2 server blades (and the access to the usb plug was really bad) :
I messed up some dimentions and had to go back to f360 to fix the problems :
(3D printing is awesome)
Final case :
Updated case for the Olimex ESP32-POE :
The code is pretty straightforward, I used a lot of existing bits and stiched everything together. It probably lacks some error checkings while posting. The SSL part of the webhook gave me some headhaches (Thanks you Alex for your help !). Make sure you include all the required librairies !
We are using Inegromat for several other projects and it is really cool to use. Values are read by the controller and then posted to Integromat via a WebHook. Integromat then stores the values in a Google sheet (we may move this to a logstash/kibana).
If one of tha values goes beyond a set theshold, an alert is send to a Slack Channel.
Wifi ... Well ... is ... Wifi ... Connexion was not reliable and the project was updated to work on an Olimex ESP32-POE https://github.com/OLIMEX/ESP32-POE. I uploaded the new code and case file.