Like many electronics hobbyists, [Pete] found that he had an overwhelming desire to build a clock for himself. He didn’t want to stick a discrete real time clock IC into a boxnd call it a day
around a microcontroller instead.
After researching the specs on a few RTC ICs, he defined some accuracy requirements for his clock, and got to building. He started out using a 32,768 Hz watch crystal, but found that the accuracy was off by about 46 ppm after only 24 hours of use. That fell well beyond his self-imposed +/- 3 ppm tolerance goal, so he purchased an oscillator with about 500 times the resolution of his previous crystal.
After writing a handful of code to ensure that the clock remains stable, he calculated that his accuracy should be about 0.18 ppm – well within his acceptable tolerance range.
[Pete] says that this is just the first part of his clock construction, and that future revisions should include plenty of additional functionality, so keep an eye out for updates.
[Alex] has reduced the resolution of his timepiece as a trade-off for speedy-readability. At least that’s what he claims
ShiftBrite to slowly alter the hue of the clock based on the current time. The concept is interesting: 12:00 starts off at white and slowly fades to green at 3:00, blue at 6:00, red at 9:00, and back to white by 12:00 to start the process over again. He has gotten to the point where he can get the time within about 15 minutes just with a quick look. But he did need to spend a few days acquiring the skill by having the color clock sit next to a traditional digital clock.
The build is pretty simple and we’d bet you already have what you need to make your own. [Alex] is really just proving a concept by using the ShiftBrite and an mBed, there’s no precision RTC involved here. So grab your microcontroller of choice, and an RGB LED of your own and see if you can’t recreate his build.
If you don’t have a 9-to-5 type of job you might find yourself constantly resetting your alarm clock as your calendar commitments change. [Lucas] finally got fed up with the nightly ritual and decided to build his ownThe display itself is an LM044L 20×4 character display. This provides a viewing area that is about 3″x1″ and since it’s an HD44780 compliant LCD screen, writing data to it takes very little effort (and RAM) compared to a graphic LCD. A PIC 18F2550 drives the device, taking input from a half-dozen buttons, driving the display, and turning on the enclosed buzzer when it’s time to get up. There’s a backup battery which will keep the settings when power is lost. The daily alarms, current time, and back light brightness can all be adjusted from the four screens that make up the settings menus. The only thing that it’s missing is a precision timekeeper, but that should be easy to add either by measuring the frequency of the mains or by using an RTC chip.
around a microcontroller instead.
After researching the specs on a few RTC ICs, he defined some accuracy requirements for his clock, and got to building. He started out using a 32,768 Hz watch crystal, but found that the accuracy was off by about 46 ppm after only 24 hours of use. That fell well beyond his self-imposed +/- 3 ppm tolerance goal, so he purchased an oscillator with about 500 times the resolution of his previous crystal.
After writing a handful of code to ensure that the clock remains stable, he calculated that his accuracy should be about 0.18 ppm – well within his acceptable tolerance range.
[Pete] says that this is just the first part of his clock construction, and that future revisions should include plenty of additional functionality, so keep an eye out for updates.
[Alex] has reduced the resolution of his timepiece as a trade-off for speedy-readability. At least that’s what he claims
ShiftBrite to slowly alter the hue of the clock based on the current time. The concept is interesting: 12:00 starts off at white and slowly fades to green at 3:00, blue at 6:00, red at 9:00, and back to white by 12:00 to start the process over again. He has gotten to the point where he can get the time within about 15 minutes just with a quick look. But he did need to spend a few days acquiring the skill by having the color clock sit next to a traditional digital clock.
The build is pretty simple and we’d bet you already have what you need to make your own. [Alex] is really just proving a concept by using the ShiftBrite and an mBed, there’s no precision RTC involved here. So grab your microcontroller of choice, and an RGB LED of your own and see if you can’t recreate his build.
If you don’t have a 9-to-5 type of job you might find yourself constantly resetting your alarm clock as your calendar commitments change. [Lucas] finally got fed up with the nightly ritual and decided to build his ownThe display itself is an LM044L 20×4 character display. This provides a viewing area that is about 3″x1″ and since it’s an HD44780 compliant LCD screen, writing data to it takes very little effort (and RAM) compared to a graphic LCD. A PIC 18F2550 drives the device, taking input from a half-dozen buttons, driving the display, and turning on the enclosed buzzer when it’s time to get up. There’s a backup battery which will keep the settings when power is lost. The daily alarms, current time, and back light brightness can all be adjusted from the four screens that make up the settings menus. The only thing that it’s missing is a precision timekeeper, but that should be easy to add either by measuring the frequency of the mains or by using an RTC chip.
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