Links

Electronics assembly [Maker Edition]

Overview

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.
Feel free to contribute and improve our documentation.
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.
And finally an example of a fully assembled system:

Visual checks

Make sure to follow the next steps. If your extension board doesn't pass these tests, please perform the necessary actions yourself before continuing.

Jumper configuration

To avoid overheating verify that jumpers are placed on the board. For the location of the jumpers, see label "jumper configuration" in the second to last graph above. Additionally see the figure below showcasing how the jumpers should be placed (in parallel to each other).

Solder bridges

Solder bridges are used to power the fans and any other 24v actuator on the board. By default the extension board is typically manufactured without solder bridges, however the new batches should contain solder bridges. See the figure below for the location of the solder bridges.
As shown in the figure below J13 already has a bridge for two fans on the +24V line and in this figure J14 + J15 do not have any solder bridges at all. Verify if J13 and J15 have a solder bridge as both need one for the operation of the fans. Optionally you may wish to connect another 24v device such as a pump, then solder the bridge for J14 on the 24+ line as well.
A solder bridge on J13 (right-side at the 24+ line). J14 and J15 are not soldered in this picture.

Connect your sensors & actuators

All the sensors and actuators are connected via connectors from the JST XH family. Collect your cables and sensors from the AstroPlant package. If you are unsure about which cable to look for you can find the right cable by looking at the color scheme used in the tables below. In addition all cables only fits a specific sensor and cannot be mismatched.

CO2 sensor

The MH-z19 CO2 sensor with connectors attached.
The CO2 sensor is of type MH-z19 with an UART interface.
CO2 sensor connection to the board.

LUX sensor

The light/lux sensor with connectors attached.
The Lux sensor is of type BH1750/GY-30 and uses an I2C interface.
The light sensor connection to the board.

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 in essence the same as a common DHT22 sensor, but has an integrated pull-up resistor.
The humidity+temperature sensor connection to the board.

LCD screen

The LCD screen is of type 16x2 + I2C backpack standard screen. See table below.
The LCD screen is connected to the 5V I2C connection.

Fans

The fans have a dimension of 10*40mm and our powered through 24VDC. The fans are typically supplied with a fixed JST-connector. Connect the fans to the extension board, the extension board contains text on the connection points for the fans. Connect an additional third fan to the spare socket.
Two fans connected to the board. Bear in mind that the Spare socket should have an additional fan.

LED panel

LED panel connection.
The LED panel is controlled via PWM signals on the extension board.
LED connection to the board (bottom connection).

Connecting the power supply

Beware that this section deal with 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 for more information. In turn we highly advice to perform this part of the assembly with an experienced electrical engineer.
The AC/DC converter detailed below should be inserted in the power casing box provided with the AstroPlant package.

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.
And finally the wiring:
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).

LED power

For the LED power connectors, find the wires with the so called spade connectors in the AstroPlant package. There should be 4 of these wires in total, in which two are needed for the LED's. The two required have a spade connector on one side and bare metal on the other side. Verify the length of them to make sure you have the right one for the LED power.
Insert the bare metal side on the LED panel 24v and GND connection. It should click in and in turn verify by pulling the cables if it is connected properly.
Bare metal (left), ferrule (right). The bare metal (single-core) wires should be used for the LED panel.
The LED panel attached to the heatsink

Assemble fan power

Similarly to the LED power section, we have two wires with spade connectors. The only difference is the cable length and the other side of the section should have a ferrule connector.

Assemble RPi power

Similarly to the Assemble fan power section, we have 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 GPIO cable supplied could have a different color scheme. The red-side shown above is in most cases another color, as there can be inconsistency between GPIO cable 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

Several tests can be performed to make sure that all electronics are setup correctly. We recommend to follow these procedures. This does mean that you'll have to detach certain modules and re-attach them after the tests succeeded.

Continuity tests

Set up

  • Detach the power supply from the extension board and LED panel.
  • Remove all the jumpers (do not forget to place them back after testing)

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 already have connected the power supply to the extension board. This is the recommended option as this setup is used in practice. See other options for alternative setups.

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.
    Connect the Raspberry Pi on the extension board with the GPIO cable (if not already done)
    • Check the jumper configuration
  2. 2.
    Turn on the 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

Similarly to option A, 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 connect 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. 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. Power off the Raspberry and remove the USB supply
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.

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 jumpers are not included in the Precious Parts section

Solder

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

PCB check

If you have soldered 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: