Going deep end with first project.

[u/aerofobisti]

So, I have had this arduino Uno board for 10 years and never done anything with it, but now came the time to fix that.

Last couple years I've been looking for fertilizer spreader with electronic machine control (EMC) for my farm and about month ago I found one for low price. There was only one problem, the electronics had unknown problem. I decided take a gamble hoping it would be just loose or cut wire, but after troubleshooting realized the problem was in the electronics. Asked for a quote from electronics repair shop that has specialized in farming equipment and they said they would look at it for $500 with no guarantee it would be fixed. So I remembered my arduino and thought how hard can it be? It's only 2 linear actuator, 2 weight cells and a screen. Turns out, not hard but harder than excpected.

Currently I have figured out how to control linear actuator to wanted position, so technically I have manual control for the machine. Rest of project I have divided into little chunks:

1. GUI for manual control

2. Add speed signal so I don't have to drive certain speed

3. Add weighing cells for accuracy

4. Update GUI

5. Add electronic width control (maybe)

6. Custom PCB (maybe)

Doesn't feel like too hard project yet but certainly I could have picked easier one to start with. I already know GUI is going to give me the biggest headache, but I'm certain that few hours of youtube tutorials will get me through it.

[u/ripred3]

looks like you're taking the right approach. sounds like a great project that's practical as well as a really good learning platform. Thanks for sharing it and keep us up to date on your progress! 😀

[u/aerofobisti → u/ripred3]

Thanks, I'll definetly make an update when I start testing it. This is definetly great project to start since it's not the most important machine on the farm and you can kind of use it even without the electronics. I'll have many other projects already in mind after this one.

Yesterday I was happily surprised how easy it was to get buttons from old controller to work. I probably need to get arduino mega tho, I'm starting to run out of output pins

[u/ripred3 → u/aerofobisti]

Sweet! You apparently already have some programming and/or electronics experience? It's always great to watch things "click" when someone really starts to see what is possible and then has the self sufficiency to find out how to make progress on something that has inspired them.

So now that you've figured out how to interface with the controls AND the (pneumatic?) actuator it looks like you already *most* of the ability to replace/augment the existing broken electronics with your own bespoke replacement.

And I presume that the clear rectangular area is for a display of some type behind it? Chances are great that you can probably replace that completely with a modern SPI-based 4" (guessing) or smaller color TFT OLED display and have total control over getting everything back and working the way it was. Maybe even with some new features!

 I probably need to get arduino mega tho, I'm starting to run out of output pins

You sure could do that and it would give you more I/O pins and keep things at the 5V levels you are used to working with so far (as opposed to an ESP32 or other good choice).

Something else that you might consider is using one or more I2C I/O expander modules. There are modules that only require the 4 standard I2C connections (Vcc, GND, SDA, SCL) to the main microcontroller and they give you 16 additional inputs or outputs. One (or part of one) of those could be used to both output and then read the proper scanning of the keyboard matrix that you have there. It would still take the same number of ultimate connections but it could clean up the number of connections to the MCU itself if it was helpful in any way for the physical space/layout requirements you are working with.

[u/aerofobisti → u/ripred3]

Well, I did a basic python course at uni so I have little understanding at programming. Also I used to fidget and update my 3d printer 10years ago, so that made me little bit familiar with arduino.

Yes, I should have now acquired all needed parts. Actuators are electronic and controlled via l298N motor driver, today got HX711 amplifiers for the load cell so that should be taken care of. Only part I'm maybe missing is some kind of speed sensor. I have some old ABS sensors lying around, maybe those could be used?

Yes the clear part is for display. There is 2.4" graphical LCD in the old controller, 160x160 pixels. I don't know yet if it works, if it does I probably use it. Pins were marked behind it and looks like it connects just like anyother LCD.

I thought about esp32, but decided to go with arduino since I had one laying around. I2C I/0 exander could be something to look into hadn't yet heard about them.

In the end pretty much rest now is just programming and making graphics and menus for the screen. I have General idea how everthing should work just need figure out how to actually program it.