Greg Smith Gives a Beloved 1970s Binary Clock a MIcroPython Upgrade with a Raspberry Pi Pico W

Maker Greg Smith has brought a vintage clock from his childhood bang up to date, adding a Raspberry Pi Pico W microcontroller board running MicroPython to a Greymark Binary Clock from the 1970s.

"When I was a boy (ca. 1978) I was an electronics hobbyist. I’d build some bizarre circuit on a breadboard and show it to my mom, who was enthusiastic, but didn’t know what it was," Smith recalls. "She asked me to build her something 'that was in a box' so she could show it to friends and relatives when they came to visit."

"At about that time we were doing an electronics segment in my high school shop class," Smith continues, "and had the chance to build a project from a kit. I shared the catalog with my mother and together we picked out the Graymark Binary Clock."

Having successfully assembled the kit, the Binary Clock — which told the time using 18 individual LED lights on the front of the wooden housing — was an instant hit. "Until the day she died she proudly displayed her Binary Clock on the mantle," Smith says. "Visitors would invariably ask about it and she’d teach them to read binary and tell the time. Sadly, a couple of years before she passed, the clock fell from the mantle and the circuit board cracked."

Having inherited the clock, Smith opted to replace its innards rather than repair the cracked board — and gave the vintage device a very modern upgrade in the process. Rather than the cracked motherboard, "heartbeat" circuit board, and primary logic board, Smith reused only the original case, LEDs — aside from one which had failed — and the control switches.

In place of the rest of the hardware, Smith installed a Raspberry Pi Pico W — a compact, low-cost development board based around Raspberry Pi's in-house dual-core RP2040 microcontroller and a dedicated Wi-Fi and Bluetooth Low Energy (BLE) radio. Initially prototyped on a breadboard then transferred to a perfboard, the replacement innards run a MicroPython program which mimics the operation of the original clock — including the ability to set the time using the original switches.

"I wanted a better interface," Smith adds. "I programmed the Bluetooth Low Energy (BLE) chip to connect to an external app. I used MicroPython’s 'bluetooth' library and a couple [of] example modules from their GitHub repo (ble_simple_peripheral and ble_advertising) to configure the BLE. [Then] I created a mini-CLI (Command-Line Interface) with a simple 'verb/object' language to control the clock."

The full project write-up is available on Smith's website, Dr. Francintosh, with source code available on GitHub under an unspecified license.