Best screen for a Pi Zero W energy monitor project - inky hat?


#1

I’m going to create a simple python project running on a Pi Zero W pulling a few bits of data from existing on-site mysql database and I want to display the data on a screen attached to the Zero W.

I want the unit in the kitchen running 24/7 showing current electricity and solar usage. These figures can change pretty quickly, ie you put the kettle on and the watts ramp up etc. So I intend pulling the figures from the database as frequently as maybe every 5 seconds and updating the display with the new figures.

I really do like the look of the inky hat but i’m worried about the refresh times for my project. Those that used the inky hat, what is it like when firing rapid amounts of changing data at it? Does it keep up?

If not the inky hat, what other options? Maybe the GFX hat? or Hyper Pixel (non touch) which seems overkill?

I don’t think any of the other lesser screens would suit.

I suppose worst case I could only send the figures every 30 seconds… same maybe the inky hat could be ok?

Any thoughts would be appreciated.


#2

Hi,

I have the red and black inky pHAT sitting on my desk showing the weather station.

As it is three colours, it really does take about 15 seconds to refresh.

Mine is set to refresh every 15 minutes, and the display flickers whilst doing so.

I imagine watching this continually flicker for 15 out of every 30 seconds would become tiresome very quickly.

The black and white one has a quicker refresh rate, at a few seconds.

Personally, if I were showing rapidly changing data I would use LEDs.

The Four Letter pHAT has a nice CPU example that is constantly refreshing.

I guess it depends on the amount of data to display, the aesthetic you are looking for etc.

This post is worth a read.

Also, The inky pHAT story.

Cheers,

Simon.


#3

Thank you.

mmmmm, Inky doesn’t seem a good fit then.

I’m looking to display something like
Solar Gen: 2345w
Consuming: 800w
Daily Gen: 8123w
Daily Cons: 2345w

With the figures constantly updating through the day.

So maybe the Hyper Pixel is the best bet?

Any cases for the HP on a Pi Zero W?


#4

The HyperPixel is an amazing screen and comes in a non touch version (and you could use web technologies to build your display and just launch a browser full screen).

I think the best alternative for your situation through would be the all new GFX Hat! https://shop.pimoroni.com/products/gfx-hat (you could even make it change colour in response to the usage!)


#5

Yeah, looks good and might be the best option. I do think the HyperPixel is overkill for this.

It wasn’t until I watched the YouTube vid did I realise that the GFX Hat allowed so much on screen. 128x64 doesn’t sound that much until you see examples. :)

Do you think the GFX Hat sit okay atop a Zero W in something like a basic Pibow case?


#6

Been thinking about this… The GFX Hat dimensions mean it will taller then the Pi Zero W? Not sure it will hang together quite right?

Yes, I could use a Pi3 (with it having the wifi) but seems totally overkill just to run a bit of a python script.

Is there any way of getting something like this small display rigged up simply to a Zero W?


#7

This fits on a Zero:

You could even use the joystick to scroll through your different input variables.

You will probably lose the top layer of the Pimoroni case though.

Not sure if this is the solution you are looking for, but food for thought.


#8

The closest I have ever come to encasing a Zero plus a pHat in a case is the pHAT badge.

I have all three colours and I have to say the smoke grey, with a Scroll pHAT HD inside it looks fantastic.

You may have to do some ziggery pokery to get it to sit flat as it is meant as a badge, but, with the zero in place it will sit at an angle on a desk.

I can probably dig one out and take a pic if needed.

Simon.


#9

Thanks Simon.

Maybe the screen i’m looking for hasn’t been made yet? A smaller Zero sized version of the GFX Hat without the buttons? Just a simple screen?

I like that pHat-badge case but I can’t see the GFX Hat working with it because of the size.

Found this on eBay and wonder if it might do a simple cheap job for a test?


#10

Ahhhh, my naivety. Obviously that 16x2 screen needs cabling to the correct pins… way past my level of expertise.

So i’m thinking sod the Zero W route, get a Pi3 and just get the GFX Hat… way more expensive and overkill for the project. But at least it will look aesthetically pleasing and allow me to display more stuff on screen. :)


#11

You could always use a 40 pin GPIO ribbon cable to connect the Pi Zero to the Hat, or a Mini Black HatHacker to put the Pi “above” the GFX Hat. There’s no reason they have to be stacked in the traditional sense.

If you did want to mount it directly on the Pi Zero, you can use two standoffs and the other side would just be a little flappy. Depends what you want to put it inside though. I have plenty of projects where I have a big HAT on the little Pi and it usually works ok.


#12

I spent a bit of time yesterday wiring up one of those 2x16 LCD displays.

Whilst it works, the display has a bigger footprint than the Zero, so finding an off the shelf case will be tricky.

As suggested above, you can break out the Zero and the HAT with a GPIO cable.

I use a slightly different GPIO cable as I have never got the normal Female to Female ‘Printer Cable’ versions to work (the cable below has a Male to Female connection so you will have to decide if this is how you want to solder up your Zero and HAT).

https://www.modmypi.com/raspberry-pi/gpio-and-breadboarding/40-pin-ribbon-cables/40-pin-gpio-male-to-female-ribbon-cable-150mm-(gertboard)

+1 for deciding on what case the finished article is going to go into.

Personally, I like old tins and you should be able to fit a Zero and that HAT inside and Altoids tin!

http://www.hackmypi.com/PiMiniMint.php

https://imgur.com/r/raspberry_pi/k0u1P

Cheers,

Simon.


#13

Thanks Both,

I’ve ordered the Pi3+ and Gfx Hat and have a PiBow case knocking about, so going to see what that all looks like for starters.

I need to concentrate some time to the coding and setup side, so happy to go with the easy plug in of the pre-built hat. :)

Will hopefully post up when i’ve got it working. :)