SenseHat object cannot be instantiated more than once.

[nralbers]

If more than a single SenseHat object is instantiated on a machine any calls to sensor data will return 0 instead of the actual sensor value.

Simple test:

from sense_hat import SenseHat
import unittest


class TestSingleton(unittest.TestCase):
    def test_singleton(self):
        sense1 = SenseHat()
        sense2 = SenseHat()
        self.assertEqual(sense1.temperature, sense2.temperature)    

if __name__ == "__main__":
    unittest.main()

This will fail on the current codebase.
I've added pull request #147 to at least prevent this occuring in a single python program by converting the SenseHat object to a thread-safe Singleton, but this will not prevent the issue arriving if multiple projects are using the SenseHat object on the same machine.

[bsimmo]

When would you have two sensehats, they would share the same i2c and other port/device numbers etc.

…

On Tue, 18 Mar 2025, 2:43 pm Natalie Romana Albers, < ***@***.***> wrote: If more than a single SenseHat object is instantiated on a machine any calls to sensor data will return 0 instead of the actual sensor value. Simple test: from sense_hat import SenseHatimport unittest class TestSingleton(unittest.TestCase): def test_singleton(self): sense1 = SenseHat() sense2 = SenseHat() self.assertEqual(sense1.temperature, sense2.temperature) if __name__ == "__main__": unittest.main() This will fail on the current codebase. I've added pull request #147 <#147> to at least prevent this occuring in a single python program by converting the SenseHat object to a thread-safe Singleton, but this will not prevent the issue arriving if multiple projects are using the SenseHat object on the same machine. — Reply to this email directly, view it on GitHub <#148>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACYAXNZNQ6BIONAUAUSTOWT2VAWI3AVCNFSM6AAAAABZILLCZKVHI2DSMVQWIX3LMV43ASLTON2WKOZSHEZDQNZXGMYTQMY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***> [image: nralbers]*nralbers* created an issue (astro-pi/python-sense-hat#148) <#148> If more than a single SenseHat object is instantiated on a machine any calls to sensor data will return 0 instead of the actual sensor value. Simple test: from sense_hat import SenseHatimport unittest class TestSingleton(unittest.TestCase): def test_singleton(self): sense1 = SenseHat() sense2 = SenseHat() self.assertEqual(sense1.temperature, sense2.temperature) if __name__ == "__main__": unittest.main() This will fail on the current codebase. I've added pull request #147 <#147> to at least prevent this occuring in a single python program by converting the SenseHat object to a thread-safe Singleton, but this will not prevent the issue arriving if multiple projects are using the SenseHat object on the same machine. — Reply to this email directly, view it on GitHub <#148>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACYAXNZNQ6BIONAUAUSTOWT2VAWI3AVCNFSM6AAAAABZILLCZKVHI2DSMVQWIX3LMV43ASLTON2WKOZSHEZDQNZXGMYTQMY> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[nralbers]

When would you have two sensehats, they would share the same i2c and other
port/device numbers etc.
…

This is not for having two physical sense hats, but for the case where the SenseHat object is instantiated in multiple places, for example if the sense object is being used in multi threaded code like in a web api running multiple worker threads.
The changes I've tested here are a guard rail because the object cannot handle being instantiated twice.