Noob in early stages of project , looking for pointers

Starting with the problem so you don't have to plough through acres of me rabbiting, I have a project that seems simple, so simple I can't find find a project like it, nor the documentation I need to determine how to do it. Plus, I don't know sufficient to even determine what technology rabbit hole I should dive down, so guidance would be appreciated. I do have confidence that I can read, understand and execute as required.

A couple of years ago, I bought some semi-decent espresso making machinery, including a manual grinder. At the time I baulked at spending the extra for any dosing options, the on demand timer version of the grinder I bought was over £100 more. I figured at the time that I would be able to judge the amount ground reasonably (or at least, sufficiently for my purposes), which proves to be largely the case. However, the option of a timed grind still seems attractive, so I've been considering how it might be achieved.

I thought Arudino or Raspberry Pi (as generic types) might be the way to go, and bearing in mind I know little about them and have never used them, started to consider the options

Features needed:

  • Ability to switch on grinder for n seconds
  • Ability to configure the number of seconds

Features desired

  • Ability to cancel process
  • Ability to override process (existing switch in parallel?)
  • Fit inside grinder case

Comparison:
Arduino | Raspberry Pi
==================== | =================
Is a dedicated control device | generic compute
Can be very small | relatively large
Low power |higher power draw
Directly control solid state relay| may need interface
inbuilt comms limited | excellent comms

That all leads me to think that the Arduino style microcontroller is the way to go, without have the faintest idea of how it will happen or what to use. This appears to be a suitable starting point, directly controlling something like a solid state relay.

My specific asks are......

Am I in the right place? is there a forum more suited than this single product one
What tech variant sounds like the best fit for this use? (ie where should I put my effort)
Are there any docs related to control inputs (ie, changing the time). In my head I have no display but three small buttons - (1) Reset (2) time up in 0.5 or 1 sec increments (3) time down. The program to control that should be fairly simple, but others may have approached this more elegantly
Am I even asking the right questions......

Without a display how do you know the number of seconds the grind is set for? You can get very small displays for very cheap, for example an OLED that is just under 1 inch (25mm). This would tell the currently set grind time. However, I don't know your exact space constraints. You could even save the time in EEPROM if you want to remember it.

An inexpensive Arduino Nano clone should be sufficient.

I saw that you were battling with tables. The easy way it to create the table in a normal editor (notepad, vi, ...) and next post it using code tags (the </> button).

Slightly more complex, the below based on Markdown Cheatsheet · adam-p/markdown-here Wiki · GitHub

Arduino Raspberry Pi
Is a dedicated control device generic compute
Can be very small relatively large
Low power higher power draw
Directly control solid state relay may need interface
inbuilt comms limited excellent comms

Tapping a button a number of times wouldn't be too arduous, it isn't something that I would frequently change, and if it is 0/5 second increments one out wouldn't make a big difference. I'd start from a base of, say, 5 seconds to further reduce the issue.

1 Like

Spot on, thanks for that. The edit box said "use BB code" - That's something I can do, I thought. Oh well..... :wink:

Yes its a practicable project. You will need to take suitable precautions as its switching mains electricity. However the code should be very straightforward. An arduino will do the job very nicely, I'd choose an arduino micro as they are inexpensive and well supported. If you put the built unit in a box you canincorporate a "wall wart" USB adaptor topower the arduino.

I have a strt of a design or something similar here

Just FYI, you can buy a timer for about USD$2

https://www.aliexpress.com/item/1005001290054150.html

Well, yeah, but where's the fun in that?

More critically

...does not a friendly domestic appliance make.

If what I'm doing was something that is necessary for function, then that might be appropriate, and the compromises that would be inevitable incorporating that and the display into something usable would be worth it. But, I want to simplify and streamline the process, I don't think that would fit the bill (I also looked at the option of using a smart plug, which again would work, but would be rather clunky).

Then this one:
https://www.aliexpress.com/item/32722946359.html

@londonham
just do it; fun project and you may be able to expand on it to add more features.

What is your level of electronics experience? To work with mains voltages and currents, you need to know how to do it safely.

That's entirely a reasonable question.

I built my first multi-band valve receiver when I was 10 in the 60's, an radio into a matchbox in the early 70s. etc.

So, quite a bit of experience, including stuff that isn't radios :wink:

For sure, if you dealt with tubes (valves) then you know about high voltage!

Somewhat coincidentally I've been going through my loft today and came across a few old "Practical Wireless" from that time, and I remembered one project I did - electronic ignition for my dad's car! (used the points to control a transistor as switch, and then some serious voltage "enhancements" that pushed 450v into the coil. That was fun, and serious voltage. I remember it teaching me a lesson or two about respect for such things.

If you want a laugh, you can see that project here https://worldradiohistory.com/UK/Practical/Wireless/70s/PW-1972-06.pdf starting on p37 of the pdf: "it in no way alters the timing; thus in the unlikely event of a component failure, a quick rearrangement of the connecting leads taking less than thirty seconds enables the car ignition to be returned to normal and the journey resumed. " :upside_down_face: :wink:

Index of /UK/Practical/Wireless (worldradiohistory.com)
Very cool resource, thank you

Ah yes, that is the good old capacitive discharge ignition project with the ability in many cases, to fire all spark plugs simultaneously! :astonished:

Would be pretty much the same as in "Electronics Australia" mag. A concept that came - and went! Not used in any production cars nowadays to my knowledge - or is it?

Gosh that takes me back! I miss those old days of electronics - If anyone wants some ge transistors I think I still have some that came (untested) from bi-pre-pak.