Zymbit Documentation

Welcome to Zymbit’s Documentation Site! Here, you will find all the resources you need to learn about and to use all Zymbit products.

Recent Activity


March 2024


Raspberry PI OS updated kernels to 6.6.y on March 12th. The kernel no longer overrides an upstream kernel decision to force the base number of the main GPIO controller to be global GPIO 0. If the ZYMKEY4 WAKE_PIN number is not set, the ZYMKEY will not bind. The install_zk_sw.sh script has been updated to set the WAKE_PIN number for you if it detects a kernel version of 6.6.x or later. If you update the kernel on an existing installation without making the change below, you will see 5 flashes per second continuously.

For RPI4, RPI5, and CM4 platforms, you will need to set the WAKE_PIN in the following manner:

Determine the numbering for GPIO4 by examining /sys/kernel/debug/gpio for the number associated with GPIO4, then set an environment variable in the Zymbit environment variable file:

sudo su
wake_pin=`grep GPIO4 /sys/kernel/debug/gpio | sed -r 's/[^0-9]*([0-9]*).*/\1/'`
echo "wake_pin=$wake_pin"   # sanity check value is set
echo "ZK_GPIO_WAKE_PIN=$wake_pin" > /var/lib/zymbit/zkenv.conf
systemctl restart zkifc

The kernel version can be retrieved with uname -r. As of version 6.6.20, the numbering is: RPI4=516 RPI5=575 CM4=516

You do not need to do anything for new installations as the install_zk_sw.sh will take care of things for you.

December 2023


We have added support for Bookworm (64-bit) on the Pi5, PI4 and CM4 for the ZYMKEY, HSM4, and HSM6. Follow the Getting Started guides to install and encrypt.

List of supported OS platforms:


supported OSs

October 2023


Secure Compute Module moved from Revision A to Revision B. The Zymbit Software did not change. The root filesystem partitioning changed from 100% of the eMMC to 50% of the eMMC (encrypted). This was done to accommodate future support for Bootware, which is available in a Preview mode. A utility is included to repartition to 100% (encrypted) if required.

See the Troubleshooting/FAQ for more information on the changes from Rev A to Rev B of the SCM itself.

September 2023


We recently pushed up a Preview for Bootware evaluation. This is for Development pur oses and not meant for Production. More details on the Preview can be found here: Bootware Preview