How do you get the attention of thousands of Hackaday readers? Build a clock! There are just so many choices to agonize over. Do you go with a crystal as a clock source, a fancy oven controlled crystal oscillator, or just mains voltage? Should you even think about putting a GPS module in a clock? All these are very interesting questions that encourage discussion or learning, and that’s what Hackaday is all about. Clocks are cool, and the engineering behind them is even cooler.
For one of [Nick]’s Hackaday Prize entries, he’s building a minimalist GPS clock. First up, the centerpiece of every clock, the display. There are eight seven-segment displays, two each for the hours, minutes, and seconds, and a smaller digit for tenths of a second. These displays are controlled by an ATXmega32E5, an upgrade on an earlier version of this project that only used an ATtiny and a MAX6951 LED driver.
The GPS wizardry is where this project gets really cool. [Nick] is using a SkyTraq Venus838LPx-T (that’s also available on a breakout board on Tindie). This GPS chip has a handy edge mount SMA connector to receive the signals from a GPS satellite, and has a bidirectional UART to dump the NMEA time codes and a PPS output. By combining the timecode, PPS output, and playing around with the timers on the microcontroller, [Nick] has a fantastically accurate clock that also looks great.