I got my RasPi-based clock to display time last night, so proof-of-concept is done.
Right now, I'm using seven b7971 tubes. All of the compute-related stuff is done via a 'C' program running on the RasPi. I had planned on adding an FPGA to offload the RasPi, but so far I have not seen a need to do that. Some of the details of the design below. I'll post a photo tonight. RasPi Zero (yeah, the $10 US board with built-in WiFi), running raspian. Debian-based tools/env, including gcc, and VNC Uses wiringPi library to allow software control of the GPIO pins Two PCB's (each with 4 sockets and current-limited direct-drive b7971 nixies). Easy to cascade more boards if I could afford more tubes. Serial interface (clk, data, load) via opto-isolators. Separate +5VDC (isolated), and +185VDC (NON-isolated) supplies Everything is working as expected; workload on the Pi is low (about 4% on average). I still need to check supply-margining, signal integrity, add the colons, and run it on the AC-line (right now it's on an isolation transformer). Hooray, no blue wires on the PCB ! Everything worked as expected the first time. There's more work to be done with the programming, such as inserting text messages. And of course, I need to make a case for it. Being able to remotely access it for software development is really handy; even after it's locked inside the case I can still login and add features. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/2d312c80-43bd-48da-afde-a008ced6ed84%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
