Zymkey LED not blinking



I just started using the ZYMKEY 3i and followed the getting started guide, i.e. installed the required package,
however, the blue led is not blinking at all. The i2c is enbaled on rpi.

Also when I do an import Zymkey in pyhton, it throws an exception.

Can you please guide me, if I did something wrong ?


Hi Sohas,

To help us help you can you please:

  • confirm which Pi you are using, and which Linux distribution
  • send a picture of your zymkey installed on RPi,
  • send us a screen shot or log of the ‘exception’.



I am using Rpi 3 model B with latest version of debian raspbian. Hope this helps.

Below is the error and image of my setup

pi@raspberrypi:~ $ sudo python
Python 2.7.9 (default, Sep 17 2016, 20:26:04)
[GCC 4.9.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import zymkey
Traceback (most recent call last):
  File "", line 1, in 
  File "/usr/local/lib/python2.7/dist-packages/zymkey/__init__.py", line 7, in 
      client = Zymkey()
  File "/usr/local/lib/python2.7/dist-packages/zymkey/module.py", line 62, in __init__ 
     raise AssertionError('bad return code {!r}'.format(ret))
AssertionError: bad return code -16


Hello Sohas,


  1. You recheck the Hardware Installation
  2. You repeat the I2C configuration process which has been updated recently (Turn i2c ON-OFF-ON, then reboot).

You can find both at:



checking back in to see if you made progress. ?


Hey Phil,

It worked after rebooting the rpi. I think enabling i2c required a reboot.

Apart from this, I encountered a software bug in ecdsa verification. When you verify with an invalid signature, it hangs rpi. The only way around is to interpret and the kill the process.

I even tested the example provided, and it also hanged for invalid signatures.


Hey Sohas,

Good to hear you got the I2C configured. We have updated Getting Started to make the I2C configuration more robust across different Pi’s and distros.

Re the ECDSA verification - we will look into that and get back to you.