These HP QDSP-6064 bubble displays have a cool retro look right out of the seventies. More practically, they allow compact numerical displays and, coupled with the HT16K33 LED driver chip, 16 digits can be displayed with only two I2C wires, power and ground. That’s a lot of display without taking up a lot of GPIO pins.

The design offers several advantages:

• no external current-limiting resistors with the HT16K33 chip
• power the display board with 3.3V or 5V
• only 4 wires to control up to 8 x 4 four-digit displays
• 8 boards can be independently addressed via solder jumpers
• small footprint at 1.46″ x 1.51″b

Arduino code to display integer and floating point numbers on the bubble display:

kriswiner/HT16K33_Display_Driver