It’s been a busy couple of days playing with the Nixie Clock but it’s been well worth it.

The firmware for the PIC is completed and running and the main logic board that contains the PIC, RS232 interface, Audio Amplifier, HT and +5v PSU is complete and working.

I had to make a few “modifications” to the wooden case as the display board PCB was slightly too wide and the 7-way Molex connector was catching on the side, preventing the board from sliding into place. Thank heavens for electric files !!

The chap who will be receiving this is a bit of a change freak and loves things that are configurable, so every parameter can be configured by hooking to clock up to a dumb RS232 terminal.

There is provision for two temperature sensors to be connected, and you can set alarms if minimum or maximum temperatures on either channel are exceeded. Alarms in either flashing coloured LED’s and/or an audio alert (frequency configurable of course).

There is provision for the CPU to power down the Nixie tubes during a specified time window. This could be useful during the day when the owner will be at work and should help extend the life of the tubes.

The on board RTC (DS1802) can have its date / time  set via a simple command over the serial port, and is also responsible for trickle-charging the on-board NiMH back up battery.

All that’s left to do is fit everything into the case and possibly make a few alterations to the firmware. I’m using just under 25% if the available program space so lots of room available for additional features. I’ve also added a 8-way Molex connector to the top of the PCB that brings out +5v, 0v and the remaining unused I/O pins from the PIC; this will make hardware expansion simpler when it’s required; and it will be required at some point.
I've also marked all the connectors so that when enquiring hands take the darn thing apart, it can be put back to gether... that's going to happen at some point as well I suspe
Picture
Picture showing back wooden panel with interface connector, logic and driver board.
 
 
Now I love clocks, I really do. They are great projects because you can place them on the mantelpiece or in other prominent locations as a functional working device, partners can’t complain about it being another piece of junk because they do something useful, they come in all sorts of shapes and sizes and are great beginner projects and once you’ve built it, you can tell people “I made that”.

Recently, I’ve been working on a new clock project and it suddenly occurred to me that except for the physical display aspect of the clock, the internals are nearly always the same. A battery-backed RTC for the date/time (usually a Dallas DS1302) with support components, a PSU section of some type that usually puts out 5v for the logic and possible an additional higher voltage for larger LED displays, a PIC to glue everything together and some display driver hardware.

The only really custom part is the physical display, and the PIC firmware, and this got me thinking; “Can I construct a generic clock that can have many different displays connected, and just need to update the PIC firmware as required”?

So, this is what I’m currently working on. Some more thought is required on some of the projects finer attributes but I have an initial prototype sat on my breadboard that’s driving a strange looking LED display with 60 LEDs on it (I’ll post pictures later) and it seems to be working well.

The next part is to design several other display units and make sure that they can be driven by the hardware.