We’ve had great fun using the Raspberry Pi’s I2C bus and Port Expanders to talk to all the registers in the system and to control the ALU. It’s such an easy to use protocol – writing to 8 pins of a Port Expander is as selecting the Port Expander and sending it a byte of data.
However, Port Expanders aren’t the only I2C device around. You can find all sorts of devices like LED dimmers, LCD drivers, Data Converters (DAC/ADC), Memories, Clocks and Audio synthesisers to name just a few.
However, I really lucked out when I came across an electronics company from southern California, Tayloredge that have ingeniously mounted a Nixie tube on a PCB with an I2C chip on-board. This simultaneously solves two major problems: it provides a neat mounting solution for the tubes and also simplifies control by using the I2C bus. Brilliant!
Not only that, but they also an accompanying fly-back boost converter that produces the 170V needed to power the tubes.
There are other modules that provide a GPS interface, a standalone real time clock and a timer. Click on the image below to see all the modules in the SmartNixie family.
This modular, well designed system presents a huge advantage to us for the Twitalu as it removes nearly all of the nitty-gritty hardware design that is required to drive and address each of the individual Nixie tubes. SmartNixie opens the door for hobbyists and hackers to integrate Nixie tubes into their projects without having to deal with the boost converters and designing a clever addressing scheme.
In the Twitalu, we will use two 5-digit and one 6-digit SmartNixie IN12 displays to show the contents of the registers. This will allow the user to see the numbers they’ve tweeted entering the system and the result at the output.