Fun with IV-18 MAX691 VFD RPI - The art of the possible

Mark TraverseMark Traverse wrote 09/16/2016 at 14:43 • 2 min read • Like

Fun with Soviet era Vacuum tubes, originally used in missile guidance systems.

Banging the bits and bytes of the IoT age.
Upstairs at Erics
Starring Raspberry PI / Node MCU / MAX 6921 / IV-18 / Python3 multiprocessing and Queuing / MQTT / I2C

One of the reasons for doing this initially on RPI was to challenge the popular belief that these displays can only really be implemented with MCU's (stability of muxing etc).. I think many peoples experiments on the PI were based on the earlier / older models and of course we now have much faster processors with the PI 3 B and while RPI will never be, and is not an R/T platform, results are reasonable.

There's plenty of vfd iv-18 clocks out there including the lady Ada ice clock but these are all atmega /arduino and pretty constrained by size of the mcu's, and (until recently) the lack of internet on these platforms - so implementations have tended to be 'just' standalone r/t clocks rather than IOT objects presenting interactive web information with text animation - which is what I wanted.

I didn't want to just take someone else's work anyway, but really go back to first principles myself to learn Python and push the boundaries of the text trickery that could be used with these displays (of course noting the constraints of seven segment). And that's where we are currently - if still at the rudiments of the prototypes.

The first incarnation in software uses Python3 and its multiprocessor library to modularise separate scripts for VFD mux and a 'supervisor' which spits out 'character frames' of 9 digits over a Python Queue to the MUX which controls the bit banging to the MAX6921 HV shift register.

Recent additions add MQTT telemetry transport between the supervisor and mux and a general notification channel into the supervisor module that allows display from anywhere. Modularising around mq telemetry will ultimately allow me to port the mux to node mcu / ESP and the device become a standalone wi-fi connected general purpose display working with my home automation.

The possibilities are endless for these beautiful displays - controlling internet radio, music playback, temperature monitoring etc and I will be building on the basic concepts to get myself fully up to speed with IOT platforms.