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Rpi Airquality Station: Indepth Assembly

Goal:

Assemble an RPi air quality Station from the parts kit, and turn it on for the first time.

What you will learn:

Special considerations for connecting sensors to the air quality hat, and how each part in the kit goes together.

What you will need:

Full RPi air quality Station kit.
The kit should contain:

Mounting Hardware:

  • Wooden backplate
  • Screws
  • Stand-offs
  • Mini-screwdriver

Electronics:

  • Two LED matrix panels
  • Two LED data ribbon cables
  • One black and red power connector
  • A raspberry pi with an SD card installed
  • An airquality hat
  • A BME-280 sensor
  • A PMS-5003 Sensor
  • A MHZ C02 sensor
  • A power supply

Getting Started:

Here are the sensors, circuit board, raspberry pi, led panels, and the piece of wood they all attach onto.

First we’ll line up the LED matrix panels. The LED matrix we use have a chained model, which means data enters one end, and is transmitted down a connected line of LED matrix panels until every pixel has been set. The arrows printed on the panels and the wood indicate the direction for data flow. Data originates in the raspberry pi, enters the air quality HAT, and goes from right to left through the LED matrix panels.

Seeing as we’re putting the panels upside down for assembly the arrows will be in a different orientation during this stage.

Once they’re flipped vertically the arrows will match up with the ones printed on the wood panel.

Seeing as data flows from one panel to another we need to connect the two using the ribbon cables.

The cable on the right will eventually be plugged into the air quality hat, but it’s less awkward if you wait until later.

 

Next we’ll attach all the sensors to the air quality hat. Here is what they look like laid out before being plugged in.

The PMS sensor is oriented with intake fan facing away from the pi, the ribbon cable is towards the bottom, as pictured, with the screw holes facing the wood.


It’s vital to keep cable orientation in mind when plugging these in, the cables and connectors are not polarized so if you aren’t very careful you could easily fry your entire air quality kit by plugging something in backwards.

First we’ll plug in the PMS-5003 air particulate sensor.

For this sensor the wire needs to make ONE twist, meaning the connector is oriented backwards on the board compared to the PMS.

Double check the way the sensor box is oriented and the cable while connecting these.

 

Next connect the BME-280 sensor

For this sensor, the cable should be lying flat against the wood without any twists, and plug straight into the air quality hat. This is the only one of the three sensors where the cable doesn’t need to be twisted.

 

Next is the MHZ C02 sensor which can be the most confusing

First check the orientation of the sensor and the hat board like in this picture. This cable has to make exactly ONE twist between the sensor and the board. You can tell if the cable is oriented correctly when the colors are flipped vertically on one side from the other. Even though it is hard to spot the twist in the above picture, you can still tell that RED is on-top on the left, and BLACK is on-top on the right; indicating that the cable has indeed made ONE twist. Your cable colors may vary from the cable pictured above.

 

Finally double check all the sensors and their connections.

Attaching sensor hat to LED matrix:

The power cables need to be attached to the sensor-hat.

Then connect the power cables  from the sensor-hat to the LED matrix panels.

Pay close attention to the polarity, the ‘GND’ text should line up with the black wires.

Screwing Everything Together:

Now that the tricky part is done we’ll start screwing everything together.

note you may have an extra screw or two for each step.

To attach the display to the wood you’ll need these parts here:

First attach the standoffs to the panel like this.

At this point your panel will have the power and data cables plugged in connecting to the Raspberry Pi and to each-other.

Use the screws through the backside of the wood to attach them like this.

Make sure to tuck the wires neatly how you want them, because the only way to adjust this later will be to take the entire thing apart again.

The final ribbon cable from earlier, coming out of the side of the LED matrix needs to be plugged into the airq uality hat as shown.

 

The ribbon cables do have a correct orientation for polarity, and this is made obvious by the latch on the connector itself.

Next attach the board and the raspberry pi to the back-plate.

Here are the parts you’ll need.

The pins in the raspberry pi will naturally line up with the socket on the air quality hat as long as the screws line up.

Here is the order that the screws and standoffs go together

This animated gif shows the assembly order.
If it’s not animated you can click on it to open it.

First screw the mini standoffs through the backplate, then the raspberry pi nestles on-top. Next the longer standoffs screw on-top of the mini-standoffs. And finally screw the sensor hat on-top of everything else.

 

Mounting the Sensors:

Next we’ll mount the sensors to the backplate.

First is the PMS which is the only one of the three sensors that uses screws. Here is a picture of how the screws go into the sensor box.

There are pre-aligned holes and an outline where it should go.

The other two sensors are simply stuck onto the board with sticky strips.

Here’s how everything looks screwed and glued down.

First Power On:

Before powering on it’s important to double check all the connector polarities against this guide.

Now it’s time for the first time node-red and grafana setup!: https://t3alliance.org/rpi-airquality-station-setting-up-the-default-flow/

 

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