Help loading 4rel4in as HAT layer 1


Staff member

You did not have write permissions in the root directory and is not a good practice to use it for any purposes.
You have to go to your user folder located in home/ folder. So type " cd home/<your_user>" then do the clone.


New member
also have this Error

>> import sm_4rel4in
>>> rel = sm_4rel4in.SM4rel4in(0)
Traceback (most recent call last):
File "/home/ryanpimg/4rel4in-rpi/python/sm_4rel4in/sm_4rel4in/", line 46, in __init__
self._card_rev_major = bus.read_byte_data(self._hw_address_, _I2C_MEM_REVISION_HW_MAJOR_ADD)
File "/usr/local/lib/python3.9/dist-packages/smbus2-0.4.2-py3.9.egg/smbus2/", line 433, in read_byte_data
ioctl(self.fd, I2C_SMBUS, msg)
OSError: [Errno 121] Remote I/O error

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/ryanpimg/4rel4in-rpi/python/sm_4rel4in/sm_4rel4in/", line 50, in __init__
raise Exception("Fail to read with exception " + str(e))
Exception: Fail to read with exception [Errno 121] Remote I/O error


Staff member
The python error tells you that it can not communicate with the card (not present or a jumper installed). Please install the command line first and test the card by running "4rel4in -list" .