After getting ready a Raspberry Pi with House Assistant to handle varied areas, I observed that one of many fundamental info of every area is temperature and humidity. We are able to purchase considered one of a number of sensors out there in the marketplace suitable with House Assistant or construct considered one of ours.
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Step 1: Necessities
I initially constructed a prototype on a breadboard to check the bottom connections and sensor studying. After being examined I outlined the system necessities. This has to:
- Enable studying of a number of sensors, together with i2c sensors
- Will be powered by battery or transformer
- Ship info to a central location to be out there in House Assistant
- Have a low consumption, particularly whether it is battery powered
- Be as small as doable in order to go unnoticed
To satisfy the above necessities I’ve outlined the next construction:
- The system is able to learn three sensors, considered one of which by way of i2c
- Lets you outline which energy mode
- Ship readings to an MQTT server in its subject in order that House Assistant can accumulate
- You should ship the readings each hour and after that enter Deep Sleep
Step 2: Prototype
Initially I expanded the bottom prototype to check the batteries. The system is able to be powered by two 18650 batteries, though it solely wants one. Utilizing two will increase the system autonomy and lets you use sensors that devour extra.
After the prototype was accomplished, I began constructing pcb on Autodesk Eagle. That is free to create PCBs as much as 11 cm.
To create the PCD in Autodesk Eagle you could create a mission and throughout the mission create a schema with the parts and their connections.
After that is created we create the pcb. For this we use the button on the toolbar. Autodesk Eagle creates a pcb with all parts and signifies their connections. Then you could outline the dimensions of the pcb, place the parts in place and make the connections between them (see extra info right here https://study.sparkfun.com/tutorials/using-eagle-board-layout/all).
Step three: Create the PCB
Lastly, it’s essential to export the drawing to gerber format to be submitted for manufacturing. As a result of there are a number of prospects, PCBWay gives a tutorial of the method (https://www.pcbway.com/helpcenter/technical_support/Generate_Gerber_files_in_Eagle.html) and which recordsdata are required to submit.
I then despatched the drawing to PCBWay for manufacturing. Thanks upfront to PCBWay for all of the help for the sponsorship.
The submission is made on the PCBWay web site. When submitting, the price is mechanically made out there. One possibility that needs to be ticked is “HASL lead free” in order that the plates don’t include lead. After submission the manufacturing course of is quick, taking 1-2 days.
Step four: Elements
After receiving the PCB’s from PCBWay, I began welding the varied parts. For this mission the next parts are required:
Step 5: Meeting
I began welding the parts on the PCB, which was a quite simple course of as a result of preparation that PCBWay does.
After soldering and a closing take a look at, I began designing the field. This was modeled on Autodesk Fusion 360. The underside, which homes the system and has the varied inputs, and the highest, which homes the DHT22. A number of covers had been additionally modeled for the inputs that won’t be used. If mandatory simply take away every lid.
Step 6: Code and Closing Steps
Lastly the code was uploaded to Wemos and put in on the spot.
The code may be downloaded from my GitHub Account.
Later I arrange House Assistant to gather the data on its matters to show within the dashboard.
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