Hi, It’s not difficult. My fumbling attempts at a Nixie clock some time ago used a 4:1 multiplex ratio, using four digits and only one decoder. I used the same MPSA42/MPSA92 driver as your example. My multiplex function was called at 100Hz, so each digit was refreshing at 25Hz. It doesn’t flicker, and (whoa!) it is working 15 years later.
The only mod I had was when switching between digits, I turned the cathode drive off for a period of 20 microseconds, before selecting the correct anode and turning on the next digit. This helped prevent ghosting. On Wednesday, 1 November 2023 at 10:14:25 UTC Richard Scales wrote: > Actually - I just looked through an example over at: > https://www.hackster.io/doug-domke/multiplexed-nixie-tube-clock-759ff5 > > ... and it all seems fairly understandable, have I overthought this? > > - Richard > > > On Wednesday, 1 November 2023 at 09:22:03 UTC Richard Scales wrote: > >> The time has come when I need to get a handle the dark and mysterious art >> of multiplexing. >> I have an understanding of what needs to happen though am mostly at a >> loss of how to implement it. >> I am broadly assuming that I should be using some kind of interrupt >> routine to make the actual display work whilst the rest of the code gets on >> with the job of working out what to display and when to display it. >> Is it even going to be feasible to have some kind of interrupt routine >> that decides what digits to light - set all the bits and then sets the >> right anode(s) on and then off again giving enough time for the persistence >> of vision to produce a non flickering display when using something like a >> wemos D1? >> >> I am thinking that the interrupt routine needs to increment which >> digit(s) is/are being illuminated - set up the right bit pattern for the >> cathodes and turn on the relevant anode(s) - wait a little and then turn >> them off again. >> My worry is that the amount of time that the displays should be left on >> might be a little too long for the ISR as my understanding is that these >> should be kept as lean as possible. >> >> Do I even need multiple interrupts (my covid addled brain is struggling >> to type let alone contemplate multiple ISR's!)? >> Can the rest of my code run in a non time critical manner as it works out >> what it wants to display where whilst the interrupt routine merryly >> illuminates digits based on values which I store in a buffer somewhere? >> ... or does the rest of my code have to work in come kind of >> state-machine fashion? >> I would expect (hope) to handle display brightness via PWM signals to HV >> Drivers. >> I have no need for cross fade effects either - just basic multiplexing of >> say 10 different multi segment displays. I am more than happy to break up >> the displays into say 2 (or more) groups in order to makes things a little >> easier. >> >> Can anyone point me in the right direction - ideally with some code >> snippets that I can use as a foundation? >> >> Just to confirm, it is only the general implementation to drive the >> displays that eludes me - the rest of the clock code is well defined and >> working well in a direct drive capacity. >> >> The desire to move to multiplexed operation is born out the the desire to >> drive a greater number of displays with a greater number of segments which >> could be done via direct drive but I foresee that multiplexing the displays >> will simplify the electronics required. >> >> So many questions I know. I would be grateful for any pointers, thank you. >> >> - Richard >> >> -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/481ed001-a396-41ab-9e9f-ce8100ded544n%40googlegroups.com.
