Build a Replica TIL311 with 22 LEDs and an ATmega328P

Back in the 1970s and 80s, Texas Instruments manufactured the TIL311 — a tiny hexadecimal chip in a translucent red package that took a 4-bit nibble and transformed it into a single hex digit on an LED display. Like most popular retro technology, TI’s TIL311 are getting harder to find, and becoming more expensive. To that end, some makers and engineers have taken to building their own version of the display, including Jacob Still and Alexander Golubow, with their DIYTIL311.

Jacob took inspiration from others who designed vintage numeric LED displays, including Hackaday user [Mile], with his DIYTIL305, and his partner’s (Golubow) PICTIL — another remake of the TIL311. This gave them the insight needed to design the DIYTIL311, which features 22 LEDs in 0201 form and powered by an ATmega328P (VQFM) microcontroller, along with some resistors (0201), and a 3-pin 16MHz ceramic resonator, all encased in red epoxy.

To simplify things, Still and Golubow decided to multiplex the LEDs to use fewer pins on the microcontroller. Jacob explains:

“So, our microcontroller needed to have 6 pins for data input (both the decimal points are independent of the control logic), and 11 output pins for the LED matrix (a 4X7 matrix was used to make routing the board easier). That’s 17 pins to start, in addition, we need 4 pins for programming (yes I could reuse the same pins, but I decided not to) and 2 pins for an external oscillator. That’s a total of 23 pins (plus VCC and GND).”

The team has created a walkthrough of their ongoing DIYTI311 build, which consists of several design schematics. As they progress, the Still and Golubow will upload new information accordingly.