Arudino | | | 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 |
no inbuilt comms * | | | excellent comms |
There are lots of timer modules (https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=digital+timer+module&_sacat=0&LH_TitleDesc=0&_odkw=digital+timer+module&_osacat=0) on eBay that could almost certainly do all that, though you'll likely need to decode a lot of Chinglish and watch some awkward YouTube demo videos to work out exactly which one you want.
Alternatively, there is an IC designed to run toasters, that you can probably repurpose:- https://www.mouser.co.uk/ProductDetail/Diodes-Incorporated/PT8A2514APE?qs=iC14BvcgY%2F2jW3uqlZRovg%3D%3D (https://www.mouser.co.uk/ProductDetail/Diodes-Incorporated/PT8A2514APE?qs=iC14BvcgY%2F2jW3uqlZRovg%3D%3D)
Consider something like the ESP-8266 or ESP-32 if you decide to go down the microcontroller route. They're small, have integrated WiFi, and a *lot* more computational grunt than the traditional ATMega Arduino boards. You can get easy to work with dev boards like the Wemos D1 mini and treat them as an Arduino (just install the relevant board definitions in the IDE).
And if you're doing that, it's probably worth checking whether Tasmota (https://tasmota.github.io/docs/) will do everything you need without you having to roll your own software.
I'm not clear about how your grinder works, but if you could do it all by switching the mains supply, you could run Tasmota (or your own Arduino/whatever code) on a Shelly (https://shelly.cloud/) or ESP-based smart plug.
The motor is AC. The capacitor is a typical "run capacitor" for a single phase AC induction motor.
What starts to give me the heebie jeebies is the comms to and from the unit, and where and how I write that, but I'm consoled by the idea that it such a fundamental part of using these bitsakit that it can't be beyond the grasp of man.
Computational power doesn't seem relevant, the core program is three, possibly four functions and I'm sufficiently pig headed to think I can manage that. What starts to give me the heebie jeebies is the comms to and from the unit, and where and how I write that, but I'm consoled by the idea that it such a fundamental part of using these bitsakit that it can't be beyond the grasp of man. Hopefully, not beyond this one either.
How about a Rasberry pi pico (https://thepihut.com/collections/pico)? Add a relay hat, a 4 digit 7 segment display hat and a couple of buttons & you should have a prototype running fairly easily.
There are lots of timer modules (https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=digital+timer+module&_sacat=0&LH_TitleDesc=0&_odkw=digital+timer+module&_osacat=0) on eBay that could almost certainly do all that, though you'll likely need to decode a lot of Chinglish and watch some awkward YouTube demo videos to work out exactly which one you want.
I had looked at them, but my impression after my initial scan of those was that it appeared unlikely to be able to fit into the case, and would therefore have to be a separate box, which is sub-optimal. The normal timing device operates in the hours scale, darkroom timers being the obvious exception, and stuff like this (https://www.ebay.co.uk/itm/333833190925?hash=item4dba023e0d:g:rK8AAOSwif9f4WPa) which is bulky or this (https://www.ebay.co.uk/itm/254602564827?hash=item3b477ed4db:g:QH0AAOSwMvtZOMs0) which is bulky and inflexible. The more you look into it the more you realise that actually, the use case I'm trying to fill is relatively esoteric. And making something up sounds like it might be fun.
The grindr has an on off non-latching switch activated by pushing the portafilter holder in. I did consider smart plugs, but that would be clunky. I'd either need to bypass the existing switch to always on, or combine the actions. Having the control on the grinder body itself is the most elegant solution.What about a Switchbot? https://www.switch-bot.com/products/switchbot-bot
[Has nobody suggested doing the whole thing with a 555 timer chip yet? You're slacking...]
If you hack the device in a wireless way then you don't have to find space and drill holes to provide a user interface and you can do all of your hackery away from the mains.
It doesn't have to WiFi or IoS though. 433 Mhz gubbins like this would allow you to put your Arduino and whatever UI you create in a separate box.
https://www.ebay.co.uk/itm/282713792696
What about a Switchbot? https://www.switch-bot.com/products/switchbot-bot
The grindr has an on off non-latching switch activated by pushing the portafilter holder in. I did consider smart plugs, but that would be clunky. I'd either need to bypass the existing switch to always on, or combine the actions. Having the control on the grinder body itself is the most elegant solution.What about a Switchbot? https://www.switch-bot.com/products/switchbot-bot
I'd suggest that this sort of thing is better served by a microcontroller (Arduino, PIC, that sort of thing) rather than an embedded Linux computer. You *really* don't need an operating system (with filesystems, booting, and all that jazz) to implement a simple timer, or even a complicated timer with network comms (though being able to use things like python and ntpd might make the development process simpler, and if you're already familiar with doing things the Raspberry Pi way, that might be reason enough to use one).With respect Kim, you need to lookup what an RPi Pico is. I have not typo'd Pi Zero.
I'd suggest that this sort of thing is better served by a microcontroller (Arduino, PIC, that sort of thing) rather than an embedded Linux computer. You *really* don't need an operating system (with filesystems, booting, and all that jazz) to implement a simple timer, or even a complicated timer with network comms (though being able to use things like python and ntpd might make the development process simpler, and if you're already familiar with doing things the Raspberry Pi way, that might be reason enough to use one).With respect Kim, you need to lookup what an RPi Pico is. I have not typo'd Pi Zero.
[Has nobody suggested doing the whole thing with a 555 timer chip yet? You're slacking...]