SimulRPi is a Python library that partly fakes RPi.GPIO and simulates some I/O devices on a Raspberry Pi (RPi).
In addition to partly faking RPi.GPIO, SimulRPi also simulates these I/O devices connected to an RPi:
- push buttons by listening to pressed keyboard keys and
- LEDs by blinking dots in the terminal along with their GPIO pin numbers.
When a LED is turned on, it is shown as a red dot in the terminal. The pynput package is used to monitor the keyboard for any pressed key. Thus, the SimulRPi library can be useful in the case that you want to try your RPi.GPIO-based script by running it on your computer when no RPi is available at the moment.
Example: terminal output
Each dot represents a blinking LED connected to an RPi and the number between brackets is the associated GPIO channel number. Here the LED on channel 22 toggles between on and off when a key is pressed.
Also, the color of the LEDs can be customized as you can see here where the LED on channel 22 is colored differently from the others.
This library is not a Raspberry Pi emulator nor a complete mock-up of RPi.GPIO, only the most important functions that I needed for my Darth-Vader-RPi project were added.
If there is enough interest in this library, I will eventually mock more functions from RPi.GPIO.
- Platforms: Linux, macOS
- Python: 3.5, 3.6, 3.7, 3.8
pynput
>=1.6.8: for monitoring the keyboard for any pressed key
It is highly recommended to install
SimulRPi
in a virtual environment using for example venv or conda.Make sure to update pip:
$ pip install --upgrade pip
Install the package
SimulRPi
with pip:$ pip install SimulRPi
It will install the dependency
pynput
if it is not already found in your system.
Make sure that pip is working with the correct Python version. It might be the case that pip is using Python 2.x You can find what Python version pip uses with the following:
$ pip -VIf pip is working with the wrong Python version, then try to use pip3 which works with Python 3.x
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To install the bleeding-edge version of the
SimulRPi
package, install it from its github repository:$ pip install git+https://github.com/raul23/SimulRPi#egg=SimulRPiHowever, this latest version is not as stable as the one from PyPI but you get the latest features being implemented.
Warning message
If you get the warning message from pip that the run_examples
script
is not defined in your PATH:
WARNING: The script run_examples is installed in '/home/pi/.local/bin' which is not on PATH.
Add the directory mentioned in the warning to your PATH by editing your configuration file (e.g. .bashrc). See this article on how to set PATH on Linux and macOS.
Test installation
Test your installation by importing SimulRPi
and printing its version:
$ python -c "import SimulRPi; print(SimulRPi.__version__)"
You can try importing RPi.GPIO
first and if it is not found, then fallback
on the SimulRPi.GPIO
module.
try:
import RPi.GPIO as GPIO
except ImportError:
import SimulRPi.GPIO as GPIO
# Rest of your code
The code from the previous example would be put at the beginning of your file with the other imports.
Or maybe you have a flag to tell whether you want to work with the simulation module or the real one.
if simulation:
import SimulRPi.GPIO as GPIO
else:
import RPi.GPIO as GPIO
# Rest of your code
The run_examples script which you have access to once you install
the SimulRPi
package allows you to run different code examples on your RPi
or computer. If it is run on your computer, it will make use of the
SimulRPi.GPIO
module which partly fakes RPi.GPIO
.
The different code examples are those presented in Examples and show the
capability of SimulRPi.GPIO
for simulating I/O devices on an RPi such as
push buttons and LEDs.
- Here is a list of the functions that implement each code example:
- Example 1: ex1_turn_on_led()
- Example 2: ex2_turn_on_many_leds()
- Example 3: ex3_detect_button()
- Example 4: ex4_blink_led()
- Example 5: ex5_blink_led_if_button()
To display the script's list of options and their descriptions:
$ run_examples -h
-e
: The number of the code example you want to run. It is required. (default: None)-m
: Set the numbering system (BCM or BOARD) used to identify the I/O pins on an RPi. (default: BCM)-s
: Enable simulation mode, i.e.SimulRPi.GPIO
will be used for simulatingRPi.GPIO
. (default: False)-l
: The channel numbers to be used for LEDs. If an example only requires 1 channel, the first channel from the provided list will be used. (default: [9, 10, 11])-b
: The channel number to be used for a push button. The default value is channel 17 which is associated by default with the keyboard key cmd_r. (default: 17)-k
: The name of the key associated with the button channel. The name must be one of those recognized by the pynput package. See the SimulRPi documentation for a list of valid key names: https://bit.ly/2Pw1OBe. Example: alt, ctrl_r (default: cmd_r)-t
: Total time in seconds the LEDs will be blinking. (default: 4)--on
: Time in seconds the LEDs will stay turned ON at a time. (default: 1)--off
: Time in seconds the LEDs will stay turned OFF at a time. (default: 1)-a
: Use ASCII-based LED symbols. Useful if you are having problems displaying the default LED signs that make use of special characters. However, it is recommended to fix your display problems which might be caused by locale settings not set correctly. Check the article 'Display problems' @ https://bit.ly/35B8bfs for more info about solutions to display problems (default: False)
Once you install the SimulRPi
package, you should have access to the
run_examples
script which can be called from the terminal by providing some
arguments.
For example:
$ run_examples -e 1 -s
Let's run the code example 5 which blinks a LED if a specified key is pressed:
$ run_examples -s -e 5 -l 22 -t 5 -k ctrl_r
Explanation of the previous command-line:
-s
: we run the code example as a simulation, i.e. on our computer instead of an RPi-e 5
: we run code example 5 which blinks a LED if a key is pressed-l 22
: we blink a LED on channel 22-t 5
: we blink a LED for a total of 5 seconds-k ctrl_r
: a LED is blinked if the keyctrl_r
is pressed
Output:
⭐
Don't forget the -s flag when running the run_examples
script as simulation,
if you want to run a code example on your computer, and not on your RPi.
The examples presented thereafter will show you how to use SimulRPi
to
simulate LEDs and push buttons.
The code for the examples shown here can be also found as a script in run_examples.
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Since we are showing how to use theSimulRPi
package, the presented code examples are to be executed on your computer. However, therun_examples
script which runs the following code examples can be executed on a Raspberry Pi or your computer.
Example 1 consists in displaying one LED on the GPIO channel 10. Here is the code along with the output from the terminal:
import SimulRPi.GPIO as GPIO
led_channel = 10
GPIO.setmode(GPIO.BCM)
GPIO.setup(led_channel, GPIO.OUT)
GPIO.output(led_channel, GPIO.HIGH)
GPIO.cleanup()
Output:
The command line for reproducing the same results for example 1 with the
run_examples
script is the following:
$ run_examples -s -e 1 -l 10
Always call GPIO.cleanup() at the end of your program to free up any resources such as stopping threads.
Example 2 consists in displaying three LEDs on channels 9, 10, and 11, respectively. Here is the code along with the output from the terminal:
import SimulRPi.GPIO as GPIO
led_channels = [9, 10, 11]
GPIO.setmode(GPIO.BCM)
GPIO.setup(led_channels, GPIO.OUT)
GPIO.output(led_channels, GPIO.HIGH)
GPIO.cleanup()
Output:
The command line for reproducing the same results for example 2 with the
run_examples
script is the following:
$ run_examples -s -e 2
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In example 2, we could have also used a
for
loop to setup the output channels and set their states (but more cumbersome):import SimulRPi.GPIO as GPIO led_channels = [9, 10, 11] GPIO.setmode(GPIO.BCM) for ch in led_channels: GPIO.setup(ch, GPIO.OUT) GPIO.output(ch, GPIO.HIGH) GPIO.cleanup()The GPIO.setup() function accepts channel numbers as
int
,list
, andtuple
. Same with the GPIO.output() function which also accepts channel numbers and output states asint
,list
, andtuple
.
Example 3 consists in detecting if the key cmd_r
is pressed and then
printing a message. Here is the code along with the output from the terminal:
import SimulRPi.GPIO as GPIO
channel = 17
GPIO.setmode(GPIO.BCM)
GPIO.setup(channel, GPIO.IN, pull_up_down=GPIO.PUD_UP)
print("Press key 'cmd_r' to exit\n")
while True:
if not GPIO.input(channel):
print("Key pressed!")
break
GPIO.cleanup()
Output:
The command line for reproducing the same results for example 3 with the
run_examples
script is the following:
$ run_examples -s -e 3 -k cmd_r
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By default,
SimulRPi
maps the keycmd_r
to channel 17 as can be seen from the default key-to-channel map.See also the documentation for SimulRPi.mapping where the default keymap is defined.
Example 4 consists in blinking a LED on channel 22 for 4 seconds (or until
you press ctrl
+ c
). Here is the code along with the output from
the terminal:
import time
import SimulRPi.GPIO as GPIO
channel = 22
GPIO.setmode(GPIO.BCM)
GPIO.setup(channel, GPIO.OUT)
start = time.time()
print("Ex 4: blink a LED for 4.0 seconds\n")
while (time.time() - start) < 4:
try:
GPIO.output(channel, GPIO.HIGH)
time.sleep(0.5)
GPIO.output(channel, GPIO.LOW)
time.sleep(0.5)
except KeyboardInterrupt:
break
GPIO.cleanup()
Output:
The command line for reproducing the same results for example 4 with the
run_examples
script is the following:
$ run_examples -s -e 4 -t 4 -l 22
Example 5 consists in blinking a LED on channel 10 for 3 seconds if the key
shift_r
is pressed. And then exiting from the program. The program can
also be terminated at anytime by pressing ctrl
+ c
. Here is the code
along with the output from the terminal:
import time
import SimulRPi.GPIO as GPIO
led_channel = 10
key_channel = 27
GPIO.setmode(GPIO.BCM)
GPIO.setup(led_channel, GPIO.OUT)
GPIO.setup(key_channel, GPIO.IN, pull_up_down=GPIO.PUD_UP)
print("Press the key 'shift_r' to turn on light ...\n")
while True:
try:
if not GPIO.input(key_channel):
print("The key 'shift_r' was pressed!")
start = time.time()
while (time.time() - start) < 3:
GPIO.output(led_channel, GPIO.HIGH)
time.sleep(0.5)
GPIO.output(led_channel, GPIO.LOW)
time.sleep(0.5)
break
except KeyboardInterrupt:
break
GPIO.cleanup()
Output:
The command line for reproducing the same results for example 5 with the
run_examples
script is the following:
$ run_examples -s -e 5 -t 3 -l 10 -b 27
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By default,
SimulRPi
maps the keyshift_r
to channel 27 as can be seen from the default key-to-channel map.See also the documentation for SimulRPi.mapping where the default keymap is defined.
To uninstall only the package SimulRPi
:
$ pip uninstall simulrpi
To uninstall the package SimulRPi
and its dependency:
$ pip uninstall simulrpi pynput
- SimulRPi documentation
- SimulRPi Changelog
- SimulRPi PyPI
- Darth-Vader-RPi: personal project using
RPi.GPIO
for activating a Darth Vader action figure with light and sounds andSimulRPi.GPIO
as fallback if testing on a computer when no RPi is available.