Command Interface

Gecko OS provides a flexible command interface that provides access to the Command API via serial and wireless/wired network interfaces.

The serial interface supports various serial protocols and modes, and is easy to use for both humans and machines alike.

Gecko OS currently supports a UART serial interface. A SPI-serial interface is planned for an upcoming release.

UART Protocol

A single or dual UART is available for use by the host MCU. If a host can support two UARTs, one UART may be used for control and data communication, and the other used for debug logging. If a single UART is available, control, data and debug logs (if enabled) are interleaved.

SPI Protocol

SPI provides a higher speed communications interface for higher bandwidth applications such as audio and video.

Commands and Streaming

Applications can use the Gecko OS Command API to send commands via a serial interface such as a UART, or a wired or wireless network interface such as Wi-Fi, Ethernet and others.

First the Gecko OS device is configured to connect to the network and to other hosts on the network. Then the Gecko OS device allows the local host to communicate with other hosts by exchanging data.

By default, the serial bus mode is set up to issue commands via the serial bus. This serial bus mode is called Command Mode.

To exchange data with other hosts, you can stream data transparently between a network interface and the local serial interface. This serial bus mode is called Stream Mode.

You can use Gecko OS commands with a range of interfaces and protocols, via the local serial bus or remotely via a network interface:

Commands can also be executed in response to GPIO assertion or reboot. See:

To configure command mode and format, see Configuring Bus Command Mode.

The local serial interface and the remote terminal are mutually exclusive: connecting a remote terminal disables the local serial interface to the command parser. See Serial Bus Mode.

The local serial interface can either stream data, or send commands and receive responses. It cannot do both simultaneously. See Serial Bus Mode.

Note: to guarantee that no characters are dropped when using the local serial interface, uart.flow must be turned on. This applies at any baud rate.

The HTTP RESTful API interface is available at all times, if the HTTP server is running and the RESTful API is enabled.

Access to the Gecko OS command parser is determined by:

Executing a Command on GPIO Assertion or Reboot - Setup GPIO

The Setup GPIO feature allows a command to be executed on reboot, GPIO assertion, or a combination of reboot and GPIO assertion. There are three modes:

To use the Setup GPIO feature, set the value of the following setup.gpio variables:

For example, the following settings cause the configuration script my_script.csv to be executed when GPIO 2 is asserted for 3 seconds during a reboot:

> set setup.gpio.cmd "setup cmd my_script.csv"
Set OK
> set setup.gpio.control_gpio 2
Set OK
> set setup.gpio.level 1
Set OK
> set setup.gpio.mode gpio
Set OK

Note: the setup.gpio.cmd variable takes a single argument. Enclose the argument in double quotes if it contains spaces, as shown above.

The following settings cause the ls command to execute automatically on reboot:

set setup.gpio.cmd "ls"
Set OK
> set setup.gpio.mode boot
Set OK
> save
> reboot
SILABS-WGM160P-4.0.0, Gecko_OS-STANDARD-4.0.12-1198, WGM160P
Executing setup.gpio.cmd: ls
> !  #   Size   Version  Filename
setup.gpio.cmd success...

Executing a Command Automatically to Set Network Credentials - Setup Auto Cmd

To execute a command automatically on boot for setting up network credentials, set the value of to the required command.

The command set in executes only when wlan.ssid is not set. It is intended to execute commands to facilitate setting up the network credentials, wlan.ssid and wlan.passkey. To execute a command independently of the state of wlan.ssid and wlan.passkey, use the Setup GPIO feature.

For example, to run the setup_web command on reboot (only if wlan.ssid is not set):

> set "setup_web"
Set OK
> save
> reboot
SILABS-WGM160P-4.0.0, Gecko_OS-STANDARD-4.0.12-1198, WGM160P
Executing setup_web
> Finding best SoftAP channel ...
IPv4 address:
HTTP and REST API server listening on port: 80
Web setup started with the SSID: Gecko OS-335 on channel 11
In progress 

Note: the variable takes a single argument. Enclose the argument in double quotes if it contains spaces, as shown above.

Executing a Script Containing Multiple Commands

You can create a configuration script with one or more commands, and execute it on reboot, or in response to asserting a GPIO.

See Configuration and Setup, Configuration Scripts.

Serial Bus Mode

Serial bus mode concerns the local UART serial interface.

A module running Gecko OS can operate in two distinct local serial bus modes, determined by the bus.mode variable:

Gecko OS commands can also be issued via the local serial interface when in STREAM mode:

The diagram below shows a schematic representation of access to the command parser via the serial interface and the Wi-Fi interface.

Note that this diagram illustrates access to the command parser only. Access via Gecko OS commands to Wi-Fi ports and other module features is unaffected by serial bus mode or remote terminal status.

Command configuration and protocols are as described in Command Mode and Command Protocol, whether commands are issued via the UART in COMMAND mode or COMMAND breakout, via the remote terminal, or via the HTTP RESTful API.

In STREAM mode, you can stream data between the UART and the Wi-Fi interface, as described in Stream Mode.

As the STREAM mode + Remote Terminal case in the above diagram suggests, you can stream data to a remote host, and at the same time issue commands to the Gecko OS device via the remote terminal or the HTTP Server RESTful API. A command issued to the command parser blocks commands from other interfaces until it is completed.

The state diagram below shows the transitions between serial bus modes.

Rebooting to COMMAND mode

To reboot to COMMAND mode, set the bus.mode variable to command, save, and reboot:

set bus.mode command

COMMAND breakout from STREAM mode

To issue commands in STREAM mode, send the breakout character sequence specified by the This is by default $$$.

Alternatively, set up a GPIO to enter command mode by enabling the GPIO function.

On switching from STREAM mode to local COMMAND mode, Gecko OS responds with Command Mode Start.

You can then issue any Gecko OS commands.

You can set bus.mode to command and save, so that on the next reboot the Gecko OS device starts in local COMMAND mode.

When you have entered local COMMAND mode from STREAM mode via a breakout sequence or GPIO, you can return to STREAM mode by issuing the exit command.

Rebooting to STREAM mode

To switch to STREAM mode from command mode, set the bus.mode variable to stream and reboot:

set bus.mode stream

Exit from COMMAND Breakout

When you have entered local COMMAND mode, or remote COMMAND mode, from STREAM mode via a breakout sequence or GPIO, you can return to STREAM mode by issuing the exit command. Gecko OS responds with Command Mode Stop. For example:

Sequences and CommandsDescription


Break out of STREAM mode
Issue some Gecko OS commands

Return to STREAM mode

Using the Remote Terminal

When the remote terminal is enabled and connected via telnet, the local command interface is disabled. However the UART can still stream to the Wi-Fi interface if the module is in STREAM mode. When a Gecko OS device is in COMMAND mode and a remote terminal is connected, disconnecting the remote terminal switches back to COMMAND mode. You can then issue commands via the local serial interface.

Enabling and Connecting the Remote Terminal

Enable the remote terminal with remote_terminal_enabled:

set remote_terminal.enabled 1

Then connect a remote device via telnet to the Gecko OS device. The default port is 2000. The host IP or name depends on the Gecko OS configuration.

For details, see the Wi-Fi Remote Terminal application note.

Bus Command Mode

Bus command mode determines whether the serial interface is used for issuing commands (command mode) or for streaming data (stream mode). The bus command mode is determined by the variable bus.mode.

In command mode the command API interface can be configured for either a human-readable format or a machine-readable format, using the variable system.cmd.format.

Note: When controlling Gecko OS via an MCU, we suggest using machine format, described below.

Configuring Bus Command Mode

The default bus mode is command. To switch to command mode, set bus.mode to command and reboot.

In command mode, the Gecko OS device effectively provides a slave interface to the host MCU. The host is the master and Gecko OS is the slave. The host initiates all transactions, which follow the sequence:

Gecko OS commands are used by the host to send control information, read and write Gecko OS variables, and to send and receive data across network connections.

In the bus command mode, the Command API interface can operate in two main formats:

The variable system.cmd.format is provided for convenience to make it easy to switch between Command API human format and machine format.

Setting system.cmd.format changes the value of several system variables to configure the desired command API format.

Human Command API Format

To configure the serial interface for human friendly operation, set system.cmd.format to human, or set the following settings.

set system.print_level all       -> Turn on all debug & informational messages
set system.cmd.header_enabled 0  -> Disable a response header
set system.cmd.prompt_enabled 1  -> Turn on the user prompt
set system.cmd.echo on           -> Turn on echo to see what you're typing

See also System Functions, Configuring Command API Format.

Machine Command API Format

To configure the serial interface for machine friendly operation, set system.cmd.format to machine, or set the following settings.

set system.print_level 0         -> Turn off all debug & informational messages
set system.cmd.header_enabled 1  -> Enable a response header (see Response format)
set system.cmd.prompt_enabled 0  -> Turn off the user prompt
set system.cmd.echo off          -> Turn off character echo

See also System Functions, Configuring Command API Format.

Command Protocol

Gecko OS commands are formatted as shown below. <command name> <arguments>\r\n where:

In the case of the get and set commands, the arguments are in the form: <variable name> <arguments> where:

The command is terminated by a carriage return and newline character (\r\n).

Manual Command Editing Features

Gecko OS provides a number of console editing features to make manual editing of commands easier.

Use the up and down arrow keys to move back and forward through the command history.

Use the left and right arrow keys to move the cursor left and right in the command.

At any point in a command or variable, press the Tab key to auto-complete.

Response Format

When system.cmd.header_enabled is true, (for example, if machine command API format has been set), responses from Gecko OS follow the format shown in the text below.

<response data>

where ...

Response Error Codes

  0 = Success
  1 = Command failed
  2 = Parse error
  3 = Unknown command
  4 = Too few args
  5 = Too many args
  6 = Unknown variable or option
  7 = Invalid argument
  8 = Serial command line buffer overflow
  9 = Bounds error, command specific, bounds of the command were exceeded

Buffering Command Responses

When reading command output by machine, longer command responses may require buffering. Gecko OS supports buffering responses for a subset of commands with the variable:


Log Format

If system.print_level is greater than 0, a log header together with one or more informational debug logs may be returned in addition to a response header and response data when a command is issued. Log headers follow the format shown in the table below.

<log message>

where ...

Escape Characters

All escape characters are delimited with a backslash.

Binary ValueEscape Value

Hex binary values may be represented as: \x<upper 4 bits><lower 4 bits>


Bus Stream Mode

As depicted in the following diagram, bus stream mode provides a transparent connection between a serial port and a network stream such as a UDP or TCP client or server. It is perfect for implementing applications such as a wireless serial port.

Bytes or characters sent from the host to a serial interface are transparently pushed by Gecko OS to a network stream via a wireless interface. Conversely, bytes or characters received by a network stream (from a remote server) via a wireless interface are transparently pushed by Gecko OS to a serial interface connected to the host. A wireless serial port is a typical application that uses stream mode.

Bus stream mode is used primarily by host applications that can handle asynchronous data (with the optional use of hardware flow control). It is perfectly suited to applications that need to use only a single network stream at any one time.

Note: While flow control is optional, we strongly recommend using flow control to prevent data loss.

For networking considerations, see Networking and Security, Serial STREAM Mode.

Configuring Bus Stream Mode

The simplest way to setup a Gecko OS device to use Stream mode is to do all the Gecko OS configuration first using command mode, then reboot into stream mode. Configuration involves just a few simple steps:

For an example, see the application note Wireless Serial Port.

Both the wlan and softap interfaces have an auto-start on bootup capability using the wlan.auto_join.enabled and softap.auto_start variables. The TCP server has auto-start capability using the tcp_server.auto_start variable. Network clients can be started using a GPIO or manually by breaking out of stream mode as described below.

Breaking out of Stream Mode

When the serial bus is in Stream mode, commands are disabled and every character sent to the serial port is automatically forwarded to a network stream. There are two ways to break out of stream mode and enable command mode entry temporarily. The first method is to send a character sequence, configurable with the, after 3 seconds of inactivity on the serial interface. By default, the stream break out sequence is $$$. The other option available to break out of stream mode is to use a GPIO configurable with the variable. When you're done entering commands, return to stream mode by issuing the exit command.

On breaking out of Stream mode, additional network connections may be available.