CCSFM DISPLAYS HAD GRADUALLY FAILED
I volunteer with the Cape Canaveral Space Force Museum, which has multiple sites both inside the secure area of the Space Force Station and one outside the perimeter - Sands History Center. Videos would play at spots around the wall of the history center detailing activities from particular launch complexes, but the devices gradually degraded based on cumulative power failures that corrupted their data.
DEVELOPED PLAN FOR NEW DISPLAY STATIONS
We came up with a design for a new display station that would employ Raspberry Pi computers, HDMI based monitors, the open source Pi Presents software and modifications I came up with to make these bulletproof. We have a range of volunteers with varying skills, plus random power outages, requiring that these new systems will work automatically and are impervious to handling errors.
I developed a printed circuit board that will plug onto the top of the Raspberry Pi (RPi), termed a 'hat' when attached to an RPi. It implements a battery, real time clock and a terminal strip to attach up to five optional switches. Pushbuttons or other sensors can be used in the future to allow visitors to choose content or to activate upon motion nearby.
The Linux system for the RPi can be set up to use an overlay file system, making the microSD card (that holds the operating system and application software) read-only. No more corruption if the RPi is not shut down properly. Pi Presents is configured to run automatically at boot up. The software runs presentations based on scheduled times we configure, thus the need for the battery protected clock. The RPi has wifi allowing us to connect to the various displays remotely to kick off special events.
The content is stored on a USB thumb drive, tailored to each station. I set up the RPi software to detect when the drive is plugged in or removed. Pi Presents is restarted for those events and we run a default show that indicates the lack of content if the thumb drive is removed.
I used an earlier prototype of my board to test out the display station, one that had additional circuitry that is unneeded. Before I decided to use the overlay file system, I was going to use supercapacitors to provide power for an automatic graceful shutdown of the RPi Linux when input power was lost. It had charging circuits as well as the power fail detection and triggers into the RPi to run the shutdown command. The new PCBs are here and the remaining components for all the stations will arrive later this week. I expect we can have them all operational within a week.
