Case Studies

Package Room Access Control System Hardware & Firmware Programming

Posted in Application Development, Circuit Design, Consumer Goods, Embedded Development & Programming, Microchip Design, Web Application Development


DMC designed a custom printed circuit board to control access to a secure package room and act as a backup power supply for a kiosk PC. DMC also implemented firmware for supervising the backup power supply and door control. 


DMC completed the electrical design and firmware programming of a custom circuit board capable of acting as an uninterruptable power supply while also abstracting the door control hardware from the main kiosk controller. 

package room PCB designed by DMC

Although uninterruptable power supplies are available as off the shelf solutions, they would have added a significant cost premium to the overall system. Because this application required the UPS to supply power only for a few minutes, DMC and the client opted to implement the UPS functionality on a custom circuit board. To save cost on the overall system, the client also requested that additional IO be included for controlling external door latches. 

Package room system PCB

DMC designed the UPS system using supercapacitors to provide power to the main system. DMC chose a supercapacitor charge management chip made by Linear Technology to coordinate the charging and power path management. An additional requirement was that the PCB notify the kiosk of power loss and force a shutdown if power was not restored. Because of this requirement, DMC opted to include an STM32 microcontroller onboard in order to allow for flexible logic and the possibility for future additions to the system. 

Learn more about DMC’s Embedded Development and Programming services

Customer Benefits

  • Low cost and small form factor Uninterruptable Power Supply (UPS) 
  • Universal door lock: the PCB is capable of being used with many standard electronic door latches which allows for future sourcing flexibility


  • Altium PCB Design Software
  • STM32 Microcontroller 
  • Linear Technology Super Capacitor Management IC