Choosing The Right RTC For Your Project

September 30, 2020 by Lewin Day 27 Comments

When it comes to measuring time on microcontrollers, there’s plenty of ways to go about things. For most quick and dirty purposes, such as debounce delays or other wait states, merely counting away a few cycles of the main clock will serve the purpose. Accurate to the tens of milliseconds, they get the average utility jobs done without too much fuss.

However, many projects are far more exacting in their requirements. When you’re building a clock, or a datalogger, or anything that relies on a stable sense of passing time for more than a few minutes, you’ll want a Real Time Clock. So called due to their nature of dealing with real time, as we humans tend to conceive it, these devices take it upon themselves to provide timekeeping services with a high degree of accuracy. We’ve compiled a guide to common parts and their potential applications so you can get things right the first time, every time.

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Watch Your Life Tick Away With This Lifetime Countdown Clock

February 6, 2020 by Dan Maloney 26 Comments

Good news, everyone! Now you can have an ongoing existential crisis, every second of your ever-dwindling life with this personal life countdown timer.

Why would anyone want to be confronted by a count of the number of seconds left until you’ve made 80 trips around the sun? We can think of plenty of reasons not to, but creator [Jia Xun Chai] thought it would be somehow motivating to see the seconds tick irretrievably by while going about his life. Thus the idea for “Lifeclocc” came to be, with its ten seven-segment displays and Teensy to tally up and display the number of seconds left in a nominal 80-year life. A DS3231 RTC module keeps it on track between power-offs. It’s not clear what happens when you hit your 80th birthday; we assume it rolls over and starts counting up as you start playing in the bonus round. No word either on what happens should you croak with time left on the clock. Answer these questions and many more by building one yourself, or you can just wait for the Kickstarter.

It took [Jia Xun] three years to develop Lifeclocc, during which time his personal life clock decreased by 94,608,000 seconds. We will say that the finished product, with its matte-finish PCB, makes a handsome timepiece. Circuit sculptor [Mohit Bhoite] took a less-angsty stab at a similar clock, the cute appearance of which is no doubt intended to blunt the pain of impending doom.

Arduino Wristwatch Has LED Hands

January 5, 2020 by Al Williams 20 Comments

When you read “Arduino wristwatch”, you fall into the trap of envisioning an Arduino UNO clumsily strapped to someone’s wrist. [Marijo Blažević’s] creation is much more polished than that. A round circuit board holds two surface mount ICs and 12 LEDs. The whole thing looks nice fit snugly inside of a watch body. It isn’t a Rolex, but it does have considerable geek cred without being unwearable in polite company.

One IC is an AVR micro, of course. The other is a DS3231 real time clock with built-in crystal. A CR2032 keeps it all running. The main body, the outer ring, the bottom, and the buttons are 3D printed in PLA. The crystal and the band are the only mechanical parts not printed. The bill of materials shows a 36mm crystal and even provides links for all the parts.

You don’t want to run LEDs all the time because it is bad on the battery. When you press the button once, you get one of the LEDs to light to show the hours. Another press reads the minutes in units of 5 minutes. A third press shows you one of five LEDs to show how many minutes to add. For example, if the time is 9:26 you’d get LED 9 (hours), LED 5 for 25 minutes, and the third press would show LED 1 for 1 extra minute. If either of the minute indicators show 12 o’clock, that indicates zero minutes.

The exciting thing, of course, is that you can program it beyond the code on GitHub. Already it can tell time and display the temperature. You don’t have a lot of I/O, but you ought to be able to get some more options and maybe some flashy LED blinking patterns in if you try.

Keeping Time With Blinkenlights

November 24, 2019 by Tom Nardi 10 Comments

If we’ve learned anything over the years, it’s that hackers like weird clocks, and they love packing as many multicolored LEDs into a device as is humanly possible. Combine both of those concepts into one project, and you’ve got a perfect storm. So as far as unnecessarily complex timepieces go, we’d say the “Crazy Clock 4” built by [Fearless Night] ranks up there among the all-time greats.

This Arduino Pro Mini powered clock syncs the current time via GPS, with a temperature compensated DS3231 RTC to keep it on the straight and narrow between satellite downlinks. Once the clock has the correct time, how do you read it? Well, at the top you’ve got a basic numerical readout for the normies, and next to that there’s a circular LED display that looks like it could double as a sci-fi movie prop. On the lower level there’s a binary clock for the real show-offs, and as if that wasn’t enough, there’s even dual color-coded analog meters to show the hours and minutes.

[Fearless Night] has provided everything you need to follow along at home, from the Arduino source code to the 3D models of the case and Gerber files for the custom PCB. Personally we think just the top half of the clock would be more than sufficient for our timekeeping needs. If nothing else it should help save some energy, as the clock currently pulls an incredible 20 watts with all those LEDs firing off.

Should you decide to take a walk down memory lane and check out some of the other interesting LED clocks we’ve featured in the past, you’d be busy for quite awhile. But for our money, it’s still hard to beat the impossibly obtuse single-LED clock.

Rise And Shine With This Japanese-Inspired Clock

November 3, 2019 by Tom Nardi 4 Comments

On the Hackaday.io page for his gorgeous “Sunrise Alarm Clock”, [The Big One] is quick to point out that his design is only inspired by Japanese lanterns, and does not use authentic materials or traditional woodworking techniques. Perhaps that’s an important fact to some, but we’ll just say that the materials used seem far less important when the end result looks this good.

Unfortunately [The Big One] hasn’t provided any interior shots of his clock, as it sounds like the aesthetics of the internal wiring isn’t quite up to the standard set by the outside of it. But he has provided a concise parts list, a wiring diagram, and source code, so we’ve got a pretty good idea of what’s under the hood.

The clock is powered by the uBBB 32u4, an ATMega32u4 development board that [The Big One] developed in conjunction with [Warren Janssens]. It uses the popular MAX7219 LED matrix for the display, and a DS3231 RTC module to help keep the time. There’s also a DFPlayer Mini module onboard that allows him to play whatever sound effects or music he wants when the alarm goes off.

Of course the star of the show is the LED strips which illuminate the shōji-style column. These have apparently been wrapped around a coffee can of all things, which not only serves as a convenient way of holding the strips, but [The Big One] says actually makes the speaker sound a bit better. Hey, whatever works.

This isn’t the first “lantern” clock to grace these pages, but compared to the high-tech presentation of previous projects, we can’t help but be impressed by the grace and elegance of this wooden masterpiece.

Casio Watch Gets A MEMS Oscillator Upgrade

February 20, 2019 by Dan Maloney 22 Comments

We’ve got to admit to being a bit of a Casio G-Shock watch geek. The big, chunky watches were every day carry items that survived everything we dished out, right up until the smartphone made wearing one seem redundant. But others continue to use and abuse G-Shocks, and some brave souls even hack them.

Replacing the standard quartz crystal with a temperature-compensated MEMS oscillator is one hack that [Alex] tried, and it appears to have worked out well. His project write-up doesn’t specify which MEMS oscillator was used, but we suspect it’s the SiT1552 TCXO. With its extremely small size, stability over a wide range of temperatures, and ultra-low power requirements, the chip is a natural choice to upgrade the stock 32.768-kHz quartz crystal of the watch. Trouble is, the tiny 1.5 mm x 0.8 mm chip-scale package (CSP) device presented some handling problems. After overcooking a few chips in the reflow oven, [Alex] was able to get one mounted to a tiny breakout board, which went into the space formerly occupied by the watch’s quartz crystal. He stole power for the TCXO from a decoupling capacitor, sealed the watch back up, and it’s back in service with better stability and longer battery life to boot. The video below shows the TCXO undergoing tests alongside the original quartz crystal and a comparatively huge DS3231 RTC module, just for fun.

[Alex]’s MEMS transplant seems a long way to go and a lot of fussy work for marginal gains, but who are we to judge? And it does make the watch susceptible to punking with a little helium, which might make things interesting.

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ESP8266 Clock Puts Time In A Jar

October 6, 2018 by Tom Nardi 13 Comments

Ironically, with the wide availability of modular electronic components today, the hardest part of constructing your latest gadget might just end up being able to find a decent looking enclosure for it. Project boxes will only get you so far, and let’s be honest, they aren’t exactly the most attractive things in the world. But if you’re willing to think outside the box (get it?) there are some unconventional options out there that might fit the bill.

Take for example this ESP8266 clock by [ZaNgAbY] that’s housed in a glass pasta jar. With the addition of some window tint film for the LED display to shine through, the final result could nearly pass as modern art. Even if you don’t need an extra clock around the house, this same general principle could be used to create a slick-looking ticker for all sorts of information, from the weather to server uptime with just some adjustments to the code.

Inside the jar there’s six 8×8 MAX7219 LED matrix modules tacked together to create one long strip, with a NodeMCU board stuck to the back with double-sided tape. There’s also a DS3231 RTC module so the clock can keep halfway decent time, but depending on how aggressively you are willing to pull down the current time from NTP, that may or may not be required. A simple barrel jack is popped through the metal lid of the jar for power, and represents the only physical connection the internals have to the outside world.

For the next iteration [ZaNgAbY] is thinking of adding a temperature and humidity sensor, and a light sensor that can dim the LED display depending on the ambient light. While the environmental sensors will have to go on the outside of the lid if there’s any hope of pulling useful readings from them, the clear glass will allow him to keep the light sensor internal to the clock.

Believe it or not, this isn’t the first time we’ve seen somebody give their electronics the pickle treatment. We’ve previously played host to a server that “preserves” files in a Mason jar, as well as a gorgeous display of an iPod under glass.

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