Using an Alternative GPIO Pin - HSM4

Remapping GPIO4 Pin

HSM4 uses GPIO4 for a ‘handshake signal’ to coordinate communications with the host Pi.
There is a logical (software), electrical and mechanical connection with GPIO4. If you need to use an alternative GPIO pin then here are the steps you need to take reconfigure your system:

Software Configuration

To remap the GPIO_4 pin used by Zymbit from GPIO4 to GPIO_X:

  1. Locate the directory ‘/var/lib/zymbit’
  2. Locate the configuration file name ‘zkenv.conf’ - if non exists then create text file ‘zkenv.conf’
  3. Into the file ‘zkenv.conf’ insert the line ZK_GPIO_WAKE_PIN=X , where X is your GPIO pin of choice.
  4. 'In the RaspberryPi file named ‘config.txt’ you will also need to explicity set GPIO_X to an input . (Note that this is the RaspberryPi config file, which is different to the zymbit conf file)
  5. Finish

Electrical Configuration

  • Electrically reconnect HSM4 pins per the diagram below.


Mechanical Configuration

  • Move HSM4 so it does not mechanically or electrically interfere with other devices connected to pins 1 thru 10.