An ESP8266 / Wemos device runs at 3v3 logic levels, the HV5622 specification indicates that it likes to run at 12V logic levels so there needs to be some conversion between the two for reliable operation.
The spec sheet for the HV5622 clearly states that the logic supply voltage should be between 10.8V and 13.2V and the logic input levels should be between supply voltage-2 and the supply voltage. Driving them with 5V logic is way out ot spec, driving with 3V3 logic even more so. I know that many folk run them at 5V logic and I have even had some success at 3V3 logic but that is way out of spec and there is a risk that things like manufacturing changes or cable lengths may stop things working one day. I was using 2N3906 level shifter circuits until Paul Andrews put me on to the CD40109 which is a nice compact 8 way level shifter (available in DIP or surface mount) which I have now used in several designs and would highly recommend. Paul, I did look briefly for the 32 bit SPI 'command' but failed to find, I should look harder and I didn't see a way of redefining the SPI pins used :-( I also found that moving the LE toggle from before the SPI commands to after made no difference as far as I could tell, both methods appeared to work equally well (for me on a WeMos). I should learn more about this. - Richard On Friday, 1 May 2020 04:56:06 UTC+1, Richard Scales wrote: > > Hello everyone, > > I am contemplating having a go at implementing some form of digit cross > fade effect of which I have zero experience, knowledge or understanding and > I am hoping that someone could point me in the right direction. > > I can see that there are established designs using HV5622 drivers which > are capable of cross fading digits that change and I'd like to implement > this myself. > > I already use the blanking signal via a PWM signal to perform overall > fading of the display (all tubes) though the trick must be maintaining full > brightness for the digits that stay static whilst varying the brightness of > the incoming and outgoing changing digits. > > If this assumption is correct then I'm also going to assume that, even for > the digits that remain static - they cannot be on all the time and there > must be some 'off' time during which the changing digits can be faded. > > This all makes use of the persistence of vision thing that makes us think > that the display is static. > > If I'm still on the right track then I am guessing that there will be a > sufficient 'off' time for the static digits to allow the fading digits > (incoming and outgoing) to be presented at varying degrees of 'brightness'. > > In a very rough pseudo code kind of thing: > > > :start of transition > Set shift register for static digits, turn all digits on, wait long enough > for the 'full display' effect', turn all digits off > Set Shift register for outgoing digits only, turn on, wait long enough > though reduce this period during the course of the transition, turn all > digits off. > Set Shift register for the incoming digits only, turn on, wait long enough > for the digits to start appearing and increase this period during the > course of the transition, turn all digits off > Loop back to start until transition is complete > > Am I anywhere near close with this? > > Is there any published method? > > I have yet to point my scope at a working clock to investigate this > further - I currently have an inherent reluctance to do this following a > recent episode of clumsy probing resulting in the premature expiration of > the device that I was investigating :-( > > It's really just the concept that I would like to fully grasp, I find that > I can stare at sample code segments all day long and not make any > meaningful progress, though code segments are most welcome. > > All pointers gleefully received. > > 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 [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/5b803a1d-75d0-4382-9c21-7f8e6961bf76o%40googlegroups.com.
