All right everyone, as promised, here are the results of the poll I made a few weeks ago. I had 24 answers, which a nice sample I think. You can still answer though.
Based on your answers, and also on what I need from this design, here are the colclusions:
- Most people think the idea of an all-in-one PCB enclosed in a rugged enclosure is a good idea. Phew!
- Most people think it would be at least nice to reduce the amount of wires needed to setup the autosteer. By grouping functions on a single board, this issue would be at least partially addressed (there is not much to do about wires across the tractor though)
- People are more divided about the digital connection means. I must admit that the question was not really clear, as it partially mixed considerations about connection and about processors. In conclusion, I thing I will focus on USB compatibility with an embedded USB hub. Ethernet is nice and has a lot of advantages (see here and here), but more complicated to implement and makes less sense on a one-board setup, in my opinion. Also, I can’t really keep both options available, I’m afraid it would be a nightmare to design.
- Almost perfect split between people who want one or tho gnss antennas! I will do my best to make these two solutions available on this PCB, using the code from MTZ8302 on ESP32.
- Most people think antennas should be removable, probably in a cost reduction approach. It doesn’t change much for the PCB, but good to know.
- Most people don’t know what’s the best position for MMA and BNO. From a physics point of view though:
- MMA can’t be impacted by metals. But it should be horizontal and maybe not too high to avoid being tossed from left to right in the field.
- BNO is used as a magnetometer (or compass), so it makes a lot of sense to put it away from metallic surfaces and outside of metallic enclosures. Kaupoi tried this anyway and, against all odds, reported it worked fine. So at this point I don’t know nothing no more! All I can tell is that i already put it on the roof once, together with MMA, both connected through 3.3V I2C with a 3m long twisted pairs cable (details here). Works fine.
I’ll output I2C on the conenctor, probably use an I2C extender like P82B96, and anyone will put MMA and BNO wherever he wants if he chooses to build a single antenna setup.
- Most people are not afraid by SMD components. It doesn’t mean they will solder them by themselves though. I’ll do what I can to source components from the JLCPCB parts library, but their catalog is not that thick so it may not be entirely possible. It was also reported that they had issues with their stock inventory. Other PCB manufacturers / assemblers can work with components you send them (like PCBWay), but the price will be higher (I didn’t do the math though).
- As said above, I will embed a USB hub on the PCB, which should satisfy a lot of people. Sorry for Ethernet enthusiasts though…
- I will output a 5V to recharge a phone, and also an adjustable DC power supply for a tablet. I personally find these useful, and a lot of people believe the same.
- Most people think the relays for sections control should be outside of the box. I didn’t expect that! But that’s understandable, as you probably are looking for modularity here. It would be a shame to have to carry a bunch of unused wired for section control when ploughing or mowing. But what if I told you that it’s possible to have 8 relays on a separate 18 pins connector, but on the same ECU box ? Damn, I don’t know about you, but that looks awesome to me! Also I’m pretty sure i can fit them inside the enclosure. I will also output USB on the other connector for people who want their own separate box, with more than 8 relays for example.
- Hydraulic lift control shouldn’t be an issue. I may use a solid state relay or MOSFETs though, for their longevity, as discussed just above with baraki.
Now, let’s design!