This project was inspired by Fran Blanche’s NIMO Tube video. It’s a fascinating video and I recommend watching it for detailed information on NIMO tube operation and history. In short, the NIMO tube was a single digit CRT display manufactured for a brief period in the late 1960’s and early 1970’s. After watching Fran’s video I really wanted to build a NIMO tube clock. Unfortunately, NIMO tubes are practically unobtainium these days. Even if you could get ahold of some they required a complex high voltage power supply to operate. I quickly abandoned the idea of a vintage NIMO clock and started looking at replicating the NIMO look with modern parts.
My design uses six 1.44-inch TFT LCD displays to display NIMO-style digits. These small LCD displays are cheap (around $3.50 US each) and use the ST7735 chipset and SPI bus. To drive the displays I’m using the Adafruit Metro M4. I found that a traditional ATmega328 based board wasn’t fast enough to update the displays once per second and didn’t have enough memory to store all the digits. The Metro M4 is fast, has plenty of memory and is compatible with the Adafruit ST7735 library.
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