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 the clock 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 are 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% of the available program space, so theres lots of room available for additional features. I’ve also added an 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 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 suspect.