I’ve finished the clock now, I mounted it to a wooden base with copper loops, secured from underneath with hot glue. I opted in the end for a DS1307 powered clock, hence the little button battery held cunningly to the bottom left. I couldn’t decide the best way to write the firmware, as reading the ds1307 takes a little too long, so it disturbs the persistence of vision effect. It therefore updates the time every minute or so, which looks a lot better.
Code is here: https://github.com/JamesGlanville/VFD
The code is a bit rubbish, as the wires on the VFD are attached semi-randomly to pins on the MAX6921, so there’s a nasty bit of magic code to work out which segments are which.
The digits are really clear in real life, it is just hard to photograph.
First!
It looks AWESOME! really nice design
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I have used the DS1307 extensively and I can assure you theres enough time to read the seconds. Set up an interrupt to trigger off a change in pin on your micro and configure the DS1307 to generate a 1Hz square wave.
The output from the output is admittedly open collector so you’ll want a pull-up resistor probably about 1Kohm but it’ll allow you to read the registers at one second intervals OR just update variables pre-loaded at stsrtup time.
May I ask more details of your rather interesting build. Specifically how you drive the VFD and especially how you obtain the relevant voltage.
MAX6675? that is a thermocouple interface chip
how can that work as a clock?