SPremote Python package

SPremote allows LEGO SPIKE Prime machines to be controlled remotely from a computer. With standard tools like Lego Education SPIKE App or Pybricks all code runs on the hub block's microcontroller. With SPremote most of the code runs on your (fast) computer, only few commands for controlling motors and readings sensors have to be executed on the (slow) hub block. With SPremote you get

• much faster programs,
• programming in your favorite Python IDE,
• orchestration of multiple hub blocks,
• (relayed) communication between multiple hub blocks,
• seamless integration of other devices like cameras,

SPremote has been developed mainly for projects in deep reinforcement learning education. All the heavy code, neural network training, optimization algorithms and so on, runs on your powerful multi-core CPU (and maybe GPU), while the LEGO machine's microcontroller only has to execute some simple commands from time to time.

Install

Install with pip from the GitHub repo:

pip install git+https://github.com/jeflem/spremote.git@main

or copy the spremote directory from the repo into your project's directory.

On the hub block you have to install LEGO SPIKE Prime firmware via Lego Education SPIKE App version 3.4.3. Other versions may work as well, but haven't been tested up to now.

Usage

Prerequisites

SPremote requires access to a serial connection to the hub block. Instructions for USB based serial connections are provided below. In principle, bluetooth connections should work, too. At least, they did with older firmware. With current 3.4.3 firmware we were not able to get a reliable connection.

SPremote has been tested on Linux only, but should work on other Unix-like systems, too. On Windows there's a good chance to get things running, if one is able to create a serial device and pass this device to pyserial.

Connect

To establish a serial USB connection to the hub block proceed as follows:

1. Connect the hub to your computer.
2. Press the hub's power button.
3. Run dmesg (or sudo dmesg) in a terminal. The last lines printed should contain information about a new USB device and it's name. Usually, it's /dev/ttyACM0.

Test connection

Before you run SPremote based Python code you may want to test the connection:

1. Run sudo screen /dev/ttyACM0 in a terminal.
2. Now you should see an empty terminal. Presse Ctrl+C.
3. Now you see the hub's Python interpreter waiting for input (>>>).
4. Write some commands, like print('test').
5. Close screen with Ctrl+a, then k, then y.

Permissions

To avoid using sudo you may have to modify permissions for device access. Choose one of the following (all tested on Debian 12):

• Run sudo chmod 666 /dev/ttyACM0 (has to be rerun after each reconnect).
• Add your user to group dialout, then logout and login again (may cause troubles if software running as a different user wants to access the hub).
• Add a udev rule (reference, access for all users, survives reconnects and reboots):
  1. sudo nano /etc/udev/rules.d/50-myusb.rules,
  2. type KERNEL=="ttyACM0",MODE="0666",
  3. close editor with Ctrl+x, then y, then return.

Test SPremote

Here is some code for testing:

import spremote

hub = spremote.Hub('/dev/ttyACM0')

print('light up one pixel')
lm = spremote.LightMatrix(hub)
lm.set_pixel(2, 2, 100)

print('change power button color')
power_button = spremote.Button(hub, 'POWER')
power_button.set_color(9)

hub.disconnect()

If you experience connection issues (device busy,...) power off the hub and power on again.

How it works

SPremote stops the Python program running on the hub by default. For this purpose SPremote sends b'\x03', which corresponds to pressing Ctrl+c in a terminal. Whenever you call an SPremote function, SPremote sends a string of Python code to the hub and waits for outputs until the hub's Python interpreter is ready for the next command.

Sending commands and retrieving outputs requires some fiddling with indentation, line breaks and other string processing issues. All this is done by the Hub class' methods. See the doc's examples section and API documentation for more information.

Documentation

Documentation is in the repo's doc/src directory (Markdown). HTML documentation is available, too.

Contributing

SPremote code lives on github.com.

File pull requests against dev branch. That branch contains the code from which the next release will be generated. The main branch contains the current stable release.