Hi! Thanks for all usefull advice! =D Even though I now know perfectly well how to interface 5V devices with 3.3V ditto I have simply decided not to. As Adam Jacobs said, the K155ID1 should be used to simplify the designs, not introduce further complexity.
The benefit of the K155ID1 is that it offers BCD to Decimal decoding with high voltage tolerant outputs. Thus only four pins are required on the µC. Four pins for the anodes and four for the cathodes will fit neatly into an 8-bit port, which will in turn allow for elegant code. However, as I don't like to design and route a separate 5V net just for 1 chip I have decided to look for something completely different. A document written by Jason Harper that I read some time ago put me on the right track. Even though the article doesn't say it explicitly I beleive that it is a form of Charlieplexing. The XMEGA, and other microcontrollers, offer not just two different modes as one usually thinks. Apart from being logical true and false a port may also become high impedive, in practice almost disconnected. Every cathode still needs a transistor of their own, but placing them in a matrix and connecting their bases and emitters in a most clever way it is possible to activate them individually using only 4 pins on the µC. Heck, this is even better than the K155ID1 since up to 12 cathodes can be steered this way, at any voltage the designer chooses (as long as the BE-junction is doesn't suffer from breakdown...) IMHO the circuit is most beautiful when Nixies with dual decimal commas are used, since the decoder is only utilized fully then. Curious readers will find the article at this site: http://nixietube.info Thanks Jason! Kind Regards Anton -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
