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Library for simple real-time control of robotic toys.

Project description


Cross platform lightweight python library to help creating interactive real-time, remote controlled toys (typically based on Raspberry Pi). Library provides set of independent reusable modules described below.

Source code can be found at

Please use pip to install this package:

pip install rstoys
pip install flask # if you plan to use rstoys.touchy
pip install arcade # if you plan to use rstoys.maps


Realtime module provides some functions related to realtime main loop processing functionality. All time or interval values are expressed in seconds.

realtime.loop(callback, update_interval=0.020)

this function enters an infinite loop calling your callback function with two parameters (elapsed_time, delta_time) at specified update_interval.

  • elapsed_time - is an absolute elapsed time in seconds starting with 0 at the beginning
  • delta_time - is a delta time in seconds since last execution of your callback function, can be used to scale your robot actions to make it more cpu load independent.

It is an equivalent of:

while True:
    callback(elapsed_time, delta_time)

Using the realtime.loop() has an advantage that it dynamically adjusts the sleep time to compensate for the time spent in your callback, trying to provide as stable callback calling interval as possible.

So far the only way to exit this loop is by pressing CTRL+C.

Example usage:

from rstoys import realtime

def update(elapsed_time, delta_time):
    print("elapsed=%08.3fs | dt=%06.3fms" % (elapsed_time, delta_time * 1000))

# initialize my hardware here

# enter the loop that calls update function every 100ms
realtime.loop(update, 0.1)

realtime.Interval(interval = 1.0)

Simplifies periodic execution with given interval.


from rstoys import realtime

every1s = realtime.Interval(1.0)
every3s = realtime.Interval(3.0)

def update(elapsed_time, delta_time):

    print("Every 100ms")

    if every1s.should(delta_time):
        print("Once per second")

    if every3s.should(delta_time):
        print("Once every 3 seconds")

realtime.loop(update, 0.1)


Provides fluent interface to map given input value via following methods, all methods are symmetrical for negative values.

.copy() # creates a copied instance

.value() # returns final value

.add(o = 0.0) # value = value + o

.mul(s = 1.0) # value = value * s

.trim(min = -1.0, max = -1.0) # trims a value into given min max range

.exp(e = math.e) # value = e ^ value

.pow(p = 1.0) # value = value ^ p

.gap(g = 0.0) # returns value if value <= -g or value >= g else 0.0

.gaplin(g = 0.0, m = 1.0) # similar to gap, but then over g interpolates linearly from 0 to m


This module provides a mobile friendly web interface with basic touch stick controller for (x, y) values that can be easily read in your python code for controlling your robot.


Starts simple flask webserver instance on a given port that is running in a separate thread this webserver can be reached:

Locally<port>/ or remotely by using your IP address of the RPi instead of


Stops touchy webserver and terminates its thread.

(x, y) = touchy.controller.getStick()

This function returns (x, y) tupple representing touch stick controller position. values are in range of [-1...0...1].

Example code:

from rstoys import touchy
from rstoys import realtime

def update(elapsed_time, delta_time):
    (x, y) = touchy.controller.getStick()
    print("elapsed=%08.3fs | dt=%06.3fms | X=%6.3f | Y=%6.3f" % (elapsed_time, delta_time * 1000, x, y))


... then open http://<YOUR-IP-ADDRESS>:5000/ in your mobile browser and move the on-screen stick to see the changes.


This module provides simple geo location related functionality to help building location aware navigation based on bearing adjustments. It properly calculates absolute bearing between two geo locations, provides correct average_bearing() method as well as simple WebMercatorProjection implementation.

Please check out file for more usage examples.

geo.LatLon(lat, lon)

geo location point with latitude and longitude

munich = geo.LatLon(48.133333, 11.566667)
# accepts also lat lon as string comma separated
munich = geo.LatLon('48.133333,11.566667')


Provides basic open-maps window rendering using arcade framework to provide visualization of geo data.

Please check out file for some usage examples.


Want to contribute? Just send me an e-mail:



Use at your own risk and have fun.

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