My Inky Phat clock - refresh speed question


I just received my Inky pHat and Pi Zero WH and put it together to make a clock. I run an NTP server on another Raspberry Pi so the idea was that I could have a physically small clock with a good display that would keep time but would sync with the NTP Pi on a regular basis.

I cobbled together some code, tested the Inky and came to the conclusion that I would need to display text in black as red takes a little too long to refresh. Needless to say the tech is great and it works really well. The simple Python script gets fired by crontab every minute and updates the display.

Now, my issue/problem is that although the Inky refreshes in about 15 seconds, the script takes around 25 seconds to run. This is my code segment for localtime, where it refreshes from the Zero’s own clock:

def LocalTime():
    Row1 = strftime('%a %d %b')   
    Row2 = strftime('%H:%M %z')   
    Row3 = 'Local Time ' + strftime('%Z')
    inkyphat.text((x, 2),  Row1, inkyphat.BLACK, font=font)
    inkyphat.text((x, 38), Row2, inkyphat.BLACK, font=font)
    inkyphat.text((x, 80), Row3, inkyphat.BLACK, font=smallfont)

Any ideas how I can speed this up, or is 25 seconds a realistic time for this setup?


I’d also like to know this. I’m trying to put together a display which shows real-time visitors to my website but it takes about 8 seconds to refresh the screen (even when not using red).

Is it possible to speed this up at all or only refresh a portion of the screen?


Generally speaking, if you need to update more than once every few minutes then you’re using the wrong display technology.

It’s not possible to make the display refresh any faster while maintaining the same level of image quality/repeatability, and it also runs the risk of damaging the display so we tend to stick well within the visual quality/speed limits.

If you want to know more than you ever might want to know about this, I’d recommend watching:


Thanks Gadgetoid!

I actually watched the video and can now understand the problem. Needless to say, it’s an amazing piece of tech especially bearing in mind the price. I’l keep running mine as a 1-minute update clock and by the time it’s worn out I’m sure the new improved version will be in stock :)