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Electronics assembly from scratch

Overview

If you manufactured your own board follow the steps below for assembly, if you ordered a pre-assembled system skip this section and please go to Casing Assembly and then Quick software setup.
Due to the manual being targeted for pilot users, we appreciate any feedback. You can contact us via mail or Slack for questions or feedback.
The following graphical overview showcases the peripheral connections to the extension board.
See the schematic below for the location of each peripheral device on the extension board.
To avoid overheating add a jumper between RPi and ln and Power RPi and JP2.

Creating the solder bridge for 24V peripherals

By default the extension board is typically manufactured without solder bridges, however for the pilot boards J13 (see image below) has typically a solder bridge. Please verify this.
As shown in the figure below J13 already has a bridge for two fans on the +24V line. For J15 connected to spare solder an additional bridge for a 3rd fan. This 3rd fan is used for pushing air towards the co2 sensor. Optionally you may wish to connect another 24v device such as a pump, then solder J14.
A solder bridge on J13 (right-side at the 24+ line)

Assemble JST connectors

All the sensors and actuators are connected via connectors from the JST XH family. It is recommended to use a PA-09 crimping tool for assembling the JST connectors.

CO2 sensor

The CO2 sensor is of type MH-z19 with an UART interface.
See table below for connection.
Use:
  • 2x 2-pin JST male
  • 2x 2-pin JST female
  • 1x 4-pin JST female
On the sensor solder the 2-pin JST males to the connections shown in the table above.
Use 22AWG cables: Red (5v), Black (GND), Rx (White), Tx (Green). Connect on the wires crimp pins with the PA-09 tool (use 1.9 mm and 1.6mm) on the sensor side.
Use the Spiral Wire wrap to wrap the wires together before connecting the other side.
Now it is time to connect the 2x 2-pin JST female on one side, keep in mind the table connections!
Now connect the 4-pin JST female on the other side and hook up to the board (Keep in mind the described table connections!, RX goes to TX on board and TX to RX). See image below.

Lux sensor

The Lux sensor is of type BH1750/GY-30 and uses an I2C interface.
See table below for the connection.
Use:
  • 1x JST 5-pin male
  • 1x JST 5-pin female
  • 1x JST 4-pin female
Solder on the sensor the JST 5-pin male.
Use 22AWG cables: Red (5v), Black (GND), SCL (Green), SDA (Yellow). Connect on the wires crimp pins with the PA-09 tool (use 1.9 mm and 1.6mm) on the sensor side.
Connect the 5-pin JST female on one side, keep in mind the table connections!
In turn apply the spiral wrap and crimp the other end of the wires.
Connect the 4-pin JST female to the wire and plug the connector in the board. (check table for connections).

Relative humidity & temperature sensor

The relative humidity and temperature sensor used in the AstroPlant kit is of type AM2302 and uses the 1-wire interface. This sensor is the same as a DHT22, but has an integrated pull-up resistor.
Use:
  • 3-pin JST female
Set spiral wrap on the existing wire and crimp the wires (see image below).
Connect the wires to the 3-pin JST female and attach to the board.

Water temperature

The water temperature sensor to be connected is of type DS18B20 and uses the 1-wire interface (Dallas/Maxim).
Use:
  • 3-pin JST female
Connect the crimps to the wires.
Connect the 3-pin JST female pin and insert into the board (data on GPIO pin 04).

LCD screen

The LCD screen is of type 16x2 + I2C backpack standard screen. See table below.
The LCD screen needs a generic 4-pin duPont connection.
On the other side set spiral wrap and construct the 4-pin JST connection for the extension board.
Plug it into the extension board in the I2C 5V section.

Fans

The fans have a dimension of 10*40mm and our powered through 24VDC. The fans are typically supplied with a JST-connector. Connect the fans to the extension board. Connect an additional fan to the spare socket. Keep in mind that the solder bridges are correct.

LED panel

The LED panel is controlled via PWM signals on the extension board. You'll need 22 AWG wires and 2x 4-pin female JST connectors.
Crimp the 22 AWG wires (colors: blue, red, yellow) and connect one 3-pin female connector on one end. In turn insert the connector into the LED.
Put spiral wrap on the wires and crimp the other side.
Crimp and connect the other 3-pin female connector to the board.
After you can detach the JST LED connector on the LED panel, as we need to glue the LED panel to the heatsink with thermal adhesive in section Assemble LED power.

Power supply assembly

Dangerous voltage/current levels. We bear no responsibility with respect to breakdowns or damages due to insufficiently safe connections. Refer to the Cern OHL v1.2 license at the top of this page. We highly advice to perform assembly with an experienced electrical engineer.
See below an overview of the power supply connections:
Technical overview (units in mm2 minimum thickness)
Recommended tools to use:
For the power supply we use the Meanwell RD 65B:
The fuse socket connector can be ordered here:
Connectors:
  • Fuse socket: Blade connector (AWG 16-14/1.5-2.5 mm2) model FBF4
  • Power supply: Spade connector U-Type (AWG 16-14/1.5-2.5 mm2)
  • Extension board terminal: Ferrule set.

Assemble AC/DC converter & fuse connector

Overview table of the power supply connections.
Start with the fuse socket connector firstly. Make sure 2x 250v 10A fuses are inserted in the fuse socket.
Open the lid and insert two fuses of 240v 10A.
See the picture below for the socket connections.
Use 2x blade connectors and 3x spade connectors. Cut 2x 1.5mm2 wires (blue, brown) for about a length of 9 cm and 1x 1.5mm2 wire (yellow-green) for a length of 12 cm. Crimp 2x the blade connectors for the blue and brown wire (remove 5.2 mm of isolation). Leave the yellow-green wire without a blade connector as that wire should be soldered to the fuse socket. Next crimp on the other side the spade U-type connector (remove 5 mm of isolation) for all wires. See figure below for an example of the final result:
Wiring of ac/dc converter to fuse socket.
Test the connections with a multi-meter. 1) perform continuity test between ground and electrical phase, 2) test if there is not short circuit in any of the power sources, 3) test the voltage levels on V1 and V2.
Adjust voltage with screw if the voltage levels are not 5v (+V1) and 24v (+V2).

Assemble LED power

  • Check the official documentation on handling the adhesives.
Firstly make sure that the heatsink is clean and doesn't contain any dust or grease. Position the heatsink according to this picture (take note of the heatsink screw holes):
Take off the LED panel and carefully apply the heatsink adhesive to the LED panel and place it on the heatsink according to the placement picture above. If you use the wakefield adhesive wait 5-46 minutes at room temperature.
The next step is to create the wires and connectors, see table below:
Use 18AWG/0.75mm2 single core wires.
Cut the red and black wires for a length of 36 cm. Remove 5 mm of isolation on both sides. Crimp 2x spade connectors on one side of the black and red wire. Solder the single core to the spade connector:
The other side of the wire goes directly into the Wago connector on the LED panel.

Assemble fan power

To power the fans you'll need 16AWG/1mm2 wires, a Ferrule crimping tool and Spade crimp tool. In addition 2x spade and 2x ferrule connectors.
Remove 5 mm of isolation on one side and 8 mm on the other side. Crimp the spade connectors one one side (5mm) of the two wires and crimp the ferrule on the other side (8mm). If you use the same ferrule crimp you can crimp at 1.5 mm.

Assemble RPi power

Similarly to the Assemble fan power section, we create two wires with spade and ferrule connectors. The only difference is the cable length.

GPIO connection between Extension board and RPi

A 40-pin GPIO cable (female/female) is needed to connect the two boards. See images below:
The red-side (top) of the cable connects to J2 on the extension board and 3.3V/5V on the Raspberry Pi.
Note that the a GPIO rainbow cable has a different color scheme. The red-side shown above is in most cases another color (there can be inconsistency between rainbow cables color schemes). The most important bit is the correct orientation.
Example GPIO configuration
GPIO cables tend to bend the GPIO-pins on the board be careful when attaching the cable.

Test the extension board

Set up

  • Don't plug the Raspberry Pi
  • Remove all the jumpers

Test the solder

  1. 1.
    Visual check all the soldered components
  2. 2.
    Continuity test on the input terminal block between:
    • 5V and GND: should not be connected
    • 24V and GND: should not be connected
    • 5V and 24V: should not be connected
    • GND and GND: should be connected
  3. 3.
    Continuity test on the sensors connectors (JST XH) between:
    • 5V and GND: should not be connected
    • 3.3V and GND: should not be connected
    • 5V and 3.3V: should not be connected
  4. 4.
    Other continuity test between:
    • Input terminal block GND and sensors connector GND: should be connected
    • Input terminal block 5V and sensors connector 5V: should not be connected

Option A: Test with the Raspberry Pi powered from the extension board

This option assumes that you have already connected the power supply to the extension board. This is the recommended option.

Set up

  • Plug a jumper on JP2
  • Plug another jumper on JP1 parallel to JP2
  • Connect the power supply on the input terminal block if you haven't already connected it (see Power supply Assembly). Don't turn the power on yet.
Test
  1. 1.
    Plug the Raspberry Pi on the extension board (be careful to align the 40-pin header)
    • Check the jumper configuration
  2. 2.
    Turn on the 5V power supply
    • The green LED of the Raspberry Pi should light on.
      • If not, turn off the power supply quickly: there is a short circuit -> check continuity of 3.3V, 5V and GND
    • The amber LED D5 on the extension board should be on
  3. 3.
    Power off the Raspberry safely

Option B: Test with the Raspberry Pi powered from USB and extension board powered from power supply

This option assumes that you have already connected the power supply to the extension board
Setup
  • Connect a 5V power supply on the input terminal block. Don't turn the power on yet.
  • Connect a USB power supply on the Raspberry Pi. Don't turn the power on yet.
  • Remove any jumper on JP2 and set a jumper on JP1 on the right hand side

Test

  1. 1.
    Plug the Raspberry Pi on the extension board (be care to align the 40-pin header)
    • Check the jumper configuration
  2. 2.
    Turn on the USB power supply and the 5V power supply
    • The green LED of the Raspberry Pi should light on.
    • The amber LED D5 on the extension board should be on
  3. 3.
    Power off the Raspberry

Option C: Test with the Raspberry Pi and extension board powered from USB

In case you have a RPi USB cable at your disposal you can follow this section. This is only suitable if you don't wish to control actuators.

Set up

  • Be sure that your Raspberry Pi alone (not plugged) is booting without troubles on the USB power supply
    • Check that the Raspberry Pi green LED (should be on)
  • Power off the Raspberry Pi
    • After it turned off remove the power supply
  • Remove all the jumper of the extension board

Test

  1. 1.
    Plug the Raspberry Pi on the extension board (be care to align the 40-pin header)
    • Check the jumper configuration
  2. 2.
    Plug the USB power supply on the Raspberry Pi
    • The green LED should light on
      • If not, unplug the power supply quickly: there is a short circuit -> check continuity of 3.3V and 5V
  3. 3.
    Power off the Raspberry and remove the USB supply
  4. 4.
    Do this test again but with a jumper on JP1 between on the RPi side and remove any jumper on JP2
    • Jumper configuration:
    • The amber LED D5 on the extension board should be on at step 2

Manufacturing your own board

Order the PCB

  • The extension board is a 2-layer FR4 PCB.
  • It is possible to order the PCB using the .kicad_pcb file or the GERBER files.
  • The parts are available on Digikey
  • The simplest way is to order the PCB and the parts from https://aisler.net/p/DBKSBTQF
    • The jumper are not include in the Precious Parts

Solder

  • It is possible by hand soldering although it is recommended to use professional equipment for SMD components.

PCB check

If you have soldered the any electronics by yourself, it is important to check the solder and the possible short circuits before powering the extension board. It may lead to irreversible damage on the Raspberry in case of short circuits.

Reference

See our Github hardware page for raw files on the PCB's: