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A novel clock display?

Posted: Tue Jan 14, 2020 3:29 pm
by pythoncoder
I'm rarely impressed by alternative clock displays firstly because the traditional analog design is so damn good. You can tell the time at a glance just from the angle between the two hands: how can you improve on that? But then I found this on the internet:
bizarre watch display
Hard to realise on a mechanical watch ;) but interesting. And it got me thinking. Some years ago I implemented analog and digital clocks on an e-paper display. In theory e-paper should be ideal for clocks with exceptionally low power consumption: zero if you switch them off! Results were poor as there are two choices. Either you refresh the display normally, in which case every (say) 1 minute the screen goes through a five second rigmarole to update. Or you use fast updates, in which case you get ghosting. I wrote it up and abandoned it.

E-paper displays in fast mode are additive. Ghosting only occurs when you turn a black pixel white. I therefore devised this adaptation of the video which only turns pixels white with a full refresh once per hour.
As in the video the display inside the circle is a window onto a dial too large to fit the screen. The dial is the minutes display, with a range of +-30 minutes. The hour hand (chevron) moves to the next hour when the minutes pass 30, with the minutes before or after the hour shown by the black band on the scale.

The above image shows 20 to 7 PM, that below shows nearly quarter past 2 PM. Like a conventional analog clock it encourages reading the display in the way in which we normally describe time.
Implemented on a Pyboard 1.x with Pervasive Displays EPD.

I'll post code in my e-paper repo in due course. Any comments or thoughts on the format?

Re: A novel clock display?

Posted: Wed Jan 15, 2020 5:20 am
by jimmo
That's very cool -- I've experimented with e-paper in the past for numerical displays and never quite got the effect I wanted.

I do really like this concept though -- both the video you linked to and your adaptation! Looking forward to testing it out on one of my displays.

Re: A novel clock display?

Posted: Wed Jan 15, 2020 6:46 am
by pythoncoder
I should add that the once per minute updates are virtually imperceptible - the display as a whole is rock-solid. You have to stare at the dial to see the black bar extend fractionally. Once an hour, on the half hour, it necessarily goes through the update performance.

Re: A novel clock display?

Posted: Thu Jan 16, 2020 3:27 pm
by pythoncoder
Code may be found here. I wrote the graphics routines with a view to easy porting to other displays, but optimising text positioning was a manual process.

Inevitably any fast mode of an e-paper display is hardware dependent.