This ‘Sidecar’ for Psion PDAs Acts as an Internet Gateway - Hackster.io

Before smartphones came along, the pinnacle of ultra-portable computing was the PDA (Personal Digital Assistant). Several manufacturers produced models implicit the years and the astir celebrated is the PalmPilot line, but they each served the aforesaid purpose: to enactment computing powerfulness successful the user’s pocket. Some precise precocious models had the quality to link to the net via WiFi oregon wired dongles, but astir models didn’t person that connectivity. To get his aged Psion PDA connected the internet, Kian Ryan built a Raspberry Pi-based “sidecar” RS232 terminal.

Ryan’s instrumentality is simply a Psion 5MX, which is simply a PDA launched successful 1999. It has a afloat QWERTY keyboard, respectable 5.6” grayscale LCD with a 640x240 resolution, a 36MHz 32-bit Arm processor, 4-16MB of RAM, and tin tally for up to 20 hours connected a brace of AA batteries. But it can’t entree the net oregon networks astatine each — astatine slightest not successful the mode modern devices (and adjacent computers of the era) do. The Psion 5MX does, however, incorporate immoderate hardware for communication: an RS-232 serial larboard and infrared. The second is highly dilatory and is truly lone suitable for sharing tiny amounts of information betwixt devices successful adjacent proximity, but the RS-232 larboard is the cardinal to this project.

Serial connection is inactive successful usage contiguous and truthful galore modern devices enactment the protocol. In this case, the Psion 5MX communicates with a Raspberry Pi Zero W via RS-232. To marque that easy, Ryan designed his ain RS-232 and null modem HAT for the Pi Zero. To marque this ‘sidecar’ self-contained, Ryan added a Pimoroni LiPo SHIM, Pimoroni LiPo Amigo Pro, and a 2200mAh LiPo battery. He crammed each of those into a customized 3D-printed enclosure to support things tidy.

The Raspberry Pi tin tally successful headless mode and the Psion 5MX tin entree its terminal done the RS-232 connection. There, it tin bash thing successful the terminal that a idiosyncratic would beryllium capable to bash if they had a keyboard connected to the Raspberry Pi itself. But Ryan took this a measurement further and setup the 2 for PPP (Point-to-Point Protocol). That lets the Psion 5MX usage the Raspberry Pi’s net transportation done the RS-232 connection. Any packets the Psion sends volition spell done RS-232 to the Raspberry Pi and past retired to the wider internet, and received packets travel the aforesaid way successful reverse.

Of course, the Psion 5MX has precise small bundle that tin instrumentality vantage of the internet. But determination is some! Ryan was capable to instal the Opera web browser connected his Psion and utilized that to entree websites — though astir are unafraid these days and aren’t accessible to aged hardware. Telnet, connected the different hand, inactive works well.