The Raspberry Pi does not perform a safe automatic shutdown when a power failure occurs, the supercapacitors will be drained and the Raspberry Pi crashes.

  • shutdown_script file not installed properly on your Raspberry Pi
  • some other setting or some other software in the Raspberry Pi is blocking the communication at the signal pin GPIO25 (GPIO23 optional).
  • the signal pin GPIO25 (GPIO23 optional) is blocked by some other hardware connected to the GPIO port in the stack.
  • after a previous reboot command the automatic shutdown function will be disabled. Use our rebootj4h script file instead of any other standard reboot commands.
  • there is another power source supplying the Raspberry Pi backward (e.g. via the signal connections). Using the Micro-USB connector on the Raspberry Pi for power supplying is not allowed. The Juice4halt has no control over this power source.  
When the Juice4halt module is removed from the Raspberry Pi, it will immediately shut down after booting.
  • This is a correct behavior, signaling that there is no connection between the Raspberry Pi and the Juice4halt module. For operating the Raspberry Pi without the Juice4halt module please deactivate or remove the shutdown_script file from the Raspberry Pi. 
The voltage at the GPIO25 pin is only 2.1V instead of a clean 3V high level.
  • The reason is an internal pull-down resistor in the Raspberry Pi. This weak internal resistor works against a 10k pull-up resistor on the Juice4halt board. Even when disabling the pull-down by a command (e.g. "gpio –g mode 25 tri") and hence raising the voltage to a 3V level, the pull-down will be activated again at the next power up.
    There is a transistor in series with the internal 10k resistor making the 10k pull-up not linear. The consequence is that pulling high is more strong at voltage levels below 2.1V than at voltage levels above 2.1V. Despite a 2.1V level, the Juice4halt is capable of safely interpreting it as a high level.

Reading the power failure information on GPIO22 does not work.
  • The Raspberry Pi's internal pull-down resistors are enabled by default. Turning the pull-down to a pull-up on GPIO22 (e.g. "gpio -g mode 22 up") will fix the problem.