Getting Started

PCB Assembly

The first step to using a GeoMCU system is getting the boards fabricated and assembled.

In general, we’ve been using JLCPCB for this, balancing time and cost. However, any PCB fabrication house should work, as long as they can create 4 layer boards. This manual will proceed assuming our existing KiCad design files and ordering from JLCPCB

Note

Switching PCB fabricators may require adjusting the board design to account for the new manufacturer’s design rules.

The basic process for this is:

1. Gerber Files

2. Get the BoM (Bill of Materials and placement files (see Assembly Files)

3. Place the order with the PCB fabrication house

4. Solder the missing signal output connector, if using External Data Acquisition.

After that, it’s time for Testing the GeoMCU Hardware.

See Ordering Hardware for more details.

Auxiliary Components

The supporting components needed depend on which configuration is in use. All configurations will require, for each PCB

• One SM-24 Geophone

• 2x modular latching connectors compatible with Molex SL

  • There are many compatible alternatives to choose from.

  • One of these will connect the geophone to the PCB, the other will connect power to it.

  • You’ll need to assemble these connectors as well, which usually involves crimping contancts onto wires then inserting them into the housings.

• Some form of Power Supply

Additionally, all configurations, even External Data Acquisition, will need a minimal network setup:

• a WiFi network operating in the 2.4 GHz band, which can be secured by at most WPA2-PSK.

  • The ESP8266 microcontrollers on the PCB cannot handle a Captive portal or any form of WPA-Enterprise and communicate in Cleartext, so we recommend running them in an isolated network. See Creating the GeoMCU Network for suggestions of how to do this.

• A PC (preferably running some kind of Linux) running an MQTT Broker

• a PC (again, preferably running Linux. Can be on the same machine as the broker) running the Gateway/Data Aggregator

Check the configuration in use for other needed components, including which Assembly Tools are necessary.

Firmware Setup

With PCB in-hand and components ready, we need to upload the PCB Firmware to the boards, as well as configure them for the local network.

For instructions, see Installing the GeoMCU Firmware. As a short summary, you’ll need to:

1. Get the source code from GitHub: NohPei/geoscope-sensor.

2. Compile it with PlatformIO or Arduino

3. Flash it to the PCB

4. Configure the sensor, either over the serial port/telnet (see Configuration), or by Flashing Configuration in Bulk

Gateway and Networking Setup

To use or test the GeoMCU sensors, you’ll need to create the GeoMCU network, consisting of:

• a 2.4 GHz WiFi network

• the MQTT Broker

• the Gateway Computer

GeoMCU Testing

When setting up with new hardware (or after an incident which could damage the PCB), it’s a good idea to test your boards before collecting vibration data. It’s also helpful to test the network by checking, for example:

• if data is being saved on the Gateway Computer by the Gateway/Data Aggregator

• if the vibration data appears as expected. You can use NohPei/GeoMCU_plotter to visualize the incoming MQTT packets to help with this

  • An oscilloscope can also be used to inspect the PCB’s output from the center pin of the BNC connector, particularly useful if the MQTT data is suspect.