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Developing Cellular Applications

After having properly setup your hardware, you just need to follow a few steps to enable cellular on your Meadow application.:

  • Configure your cellular provider and connection.
  • Configure the Meadow pins and network setting.
  • Handle cell connection and start making network requests

Step 1: Adding a cell.config.yaml file​

Create a cell.config.yaml file, set the Copy To Output property to Copy always or Copy if newer, and fill out the values under the Settings section like APN, Module, and a additional optional pins to ensure a proper connection with your internet provider. Here's what a cell config file looks like with the required and optional fields:

Settings:
    APN: YOUR-APN         # (required) Access Point Name
    Module: BG95M3        # (required) Module model (BG95M3 or M95)
    User: USER            # (optional) APN user
    Password: PASSWORD    # (optional) APN password
    Operator: 00000       # (optional) Carrier numeric operator code
    Mode: CATM1           # (optional) Network mode (CATM1, NBIOT or GSM)
    Interface: COM1       # (required) Serial interface (COM1 (default), COM4 or COM6)
    EnablePin: A3         # (required) Enable MCU pin to power the module on/off
                          # Default value is MCU Pin A3
                          #   IMPORTANT:
                          #   Ensure to use the MCU pin names,
                          #   not the Meadow pin names (seen on the board)

A few things to consider:

  • Ensure to use the MCU pin names in the EnablePin field, not the Meadow pin names (seen on the board). Consult the pinout definition on your Meadow device datasheet for the correct MCU pin names.
  • If the carrier numeric operator code (Operator) or the network mode is not specified (Mode), the module will attempt to automatically determine the optimal network based on the M2M sim card inserted and your location.
  • However, if you encounter any connectivity issues, we recommend to set both the operator code and operation mode to the Operator and Mode properties. If you don't know this information, you can use the Cell Network Scanner method that will list nearby networks in the area.

Step 2: Specify Network Interface and reserved pins​

In the meadow.config.yaml file, you need to specify DefaultInterface to Cell and specify the RX/TX serial pins and an additional pin for Meadow to enable the cellular module.

Configuring Meadow F7v2 Feather with BG95-M3 or M95​

If you're using a Meadow Feather V2, you would connect the cellular module to D00 and D01, which are the COM4 serial pins that, according to the datasheet, the MCU pin names are PI9 and PH13, but in the config file we can ommit the p prefix. As for the enable pin, say if you connect it to the D10 pin, the MCU pin name is C7. So the required values in the config files should look like this:

# Device specific config
Device:
    # Name of the device
    Name: F7v2Feather

    # Corresponding MCU pin names for the reserved pins
    # (COMX_RX pin, COM_TX pin, ENABLE pin)
    ReservedPins: I9;H13;C7

# Network configuration
Network:
    #  Which interface should be used?
    DefaultInterface: Cell

And your EnablePin and Interface in the cell.config.yaml should be C7 and COM4, respectively:

Settings:
...
    Interface: COM4       # (required) Serial interface (COM1 (default), COM4 or COM6)
    EnablePin: C7         # (required) Enable MCU pin to power the module on/off

Configuring Project Lab v3 with BG95-M3​

In the case that you're using a Project Lab v3 with the BG95-M3, if you look at the latest schematic and trace what pins on the Meadow Core Compute Module are connected to the microBUS 1 connector, you'll find that are connected to pins PB15, PB14 and PA3 for the Serial RX/TX and Enable pins, respectively:

# Device specific config
Device:
    # Name of the device
    Name: ProjectLabV3

    # Corresponding MCU pin names for the reserved pins
    # (COMX_RX pin, COM_TX pin, ENABLE pin)
    ReservedPins: B15;B14;A3

# Network configuration
Network:
    #  Which interface should be used?
    DefaultInterface: Cell

And your EnablePin and Interface in the cell.config.yaml should be A3 and COM1, respectively:

Settings:
...
    Interface: COM1       # (required) Serial interface (COM1 (default), COM4 or COM6)
    EnablePin: A3         # (required) Enable MCU pin to power the module on/off

Configuring Project Lab v3 with M95​

In the case that you're using a Project Lab v3 with the M95, if you look at the latest schematic and trace what pins on the Meadow Core Compute Module are connected to the microBUS 1 connector, you'll find that are connected to pins PB15, PB14 and PH10 for the Serial RX/TX and Enable pins respectively:

# Device specific config
Device:
    # Name of the device
    Name: ProjectLabV3

    # Corresponding MCU pin names for the reserved pins
    # (COMX_RX pin, COM_TX pin, ENABLE pin)
    ReservedPins: B15;B14;H10

# Network configuration
Network:
    #  Which interface should be used?
    DefaultInterface: Cell

And your EnablePin and Interface in the cell.config.yaml should be H10 and COM1, respectively:

Settings:
...
    Interface: COM1        # (required) Serial interface (COM1 (default), COM4 or COM6)
    EnablePin: H10         # (required) Enable MCU pin to power the module on/off

Configuring Project Lab v3 with EG21​

In the case that you're using a Project Lab v3 with the EG21-GL module on mikroBUS 1 you'll need this in your meadow.config.yaml:

# Device specific config
Device:
    # Name of the device
    Name: ProjectLabV3

    # Corresponding MCU pin names for the reserved pins
    # (COMX_RX pin, COM_TX pin, ENABLE pin)
    ReservedPins: B15;B14;H10

# Network configuration
Network:
    #  Which interface should be used?
    DefaultInterface: Cell
...

And your EnablePin and Interface in cell.config.yaml should be H10 and COM1, respectively:

Settings:
...
    Interface: COM1        # (required) Serial interface (COM1 (default), COM4 or COM6)
    EnablePin: H10         # (required) Enable MCU pin to power the module on/off

Step 3: Handling Cell connection using a Meadow application​

To check if you established a connection, you can use the meadow listen CLI command, which should return a message like this: Connection established successfully! IP address '100.69.106.222'.

You can also check the Cell connection status by accessing the IsConnected property present in the ICellNetworkAdapter, as in the following example:

var cell = Device.NetworkAdapters.Primary<ICellNetworkAdapter>();

if (cell.IsConnected)
{
    Console.WriteLine("Cell is connected!");
}
else
{
    Console.WriteLine("Cell isn't connected");
}

Therefore, you can use the NetworkConnected and NetworkDisconnected event handlers with Cell.

var cell = Device.NetworkAdapters.Primary<ICellNetworkAdapter>();

cell.NetworkConnected += CellAdapter_NetworkConnected;
cell.NetworkDisconnected += CellAdapter_NetworkDisconnected;

void CellAdapter_NetworkConnected(INetworkAdapter networkAdapter, NetworkConnectionEventArgs e)
{
    Resolver.Log.Info("Cell network connected!");
}

void CellAdapter_NetworkDisconnected(INetworkAdapter networkAdapter)
{
    Resolver.Log.Info("Cell network disconnected!");
}

That's all! After that you should get connected. If you are having issues to connect using cellular, please take a look at the Troubleshooting section.

You can also take a look at the Cellular Meadow Sample App to help you on your first steps with cell!

Getting module IMEI​

You can get the International Mobile Equipment Identity (IMEI) through the Imei property.

var cell = Device.NetworkAdapters.Primary<ICellNetworkAdapter>();

cell.NetworkConnected += CellAdapter_NetworkConnected;

void CellAdapter_NetworkConnected(INetworkAdapter networkAdapter, INetworkAdapter networkAdapter)
{
    Resolver.Log.Info("Cell network connected!");

    ICellNetworkAdapter cellAdapter = networkAdapter as ICellNetworkAdapter;
    if (cellAdapter != null)
    {
        Console.WriteLine("Cell IMEI: " + cellAdapter.Imei);
    }
}

Note: Before using this property, ensure a successful connection has been established.

Getting Cell Signal Quality​

You can get the Cell Signal Quality (CSQ), in dBm, obtained at the time of the connection through the Csq property, which is updated after any connection network event.

var cell = Device.NetworkAdapters.Primary<ICellNetworkAdapter>();

cell.NetworkConnected += CellAdapter_NetworkConnected;

void CellAdapter_NetworkConnected(INetworkAdapter networkAdapter, INetworkAdapter networkAdapter)
{
    Resolver.Log.Info("Cell network connected!");

    ICellNetworkAdapter cellAdapter = networkAdapter as ICellNetworkAdapter;
    if (cellAdapter != null)
    {
        Console.WriteLine("Cell CSQ: " + cellAdapter.Csq);
    }
}

To get the most up-to-date Cell Signal Quality (CSQ), you should use the GetSignalQuality method instead of relying on the Csq property. However, you'll be disconnected from the cellular network for a brief period while the module gets the current signal quality, so it's advised to avoid calling this method frequently to ensure a seamless user experience.

var cell = Device.NetworkAdapters.Primary<ICellNetworkAdapter>();

double csq  = cell.GetSignalQuality();
Console.WriteLine("Cell Signal Quality: " + csq);

Note: Both the Csq property and the GetSignalQuality method return a value in dBm representing the Cellular Signal Quality (CSQ), while -9999 indicates no connection.

Additional resources​

If you have trouble connecting to your cellular network, check out the Troubleshooting guide for some tips on how to scan for available networks and check the cellular network connection logs.

If your cellular module supports it, you can also do GNSS positioning with the cellular module. Check out the GNSS with Cellular guide for more information.