Could this work?
GN4 is a ground point for MD13 and 6/2 valve.
Is that the wrong way around? The protection diode on the left will always flow GN4 to GND looking at that drawing. Could also be P type to switch the 12v side rather than GND side?
Edit: I always think in my head these two rules
-
Diodes - Line to Gnd if you want to flow.
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Mosfets - Source to Source (Battery), Drain to Load (Light/Motor/Valve), Gate pulled to Source = Stop, Gate pulled away from Source = Go.
N channel supply the Ground - Source must be battery Ground.
P channel supply the Power - Source must be battery Power. (Example IRF9540N )
This picture has both options ( I just prefer to have all 3 coils the same ), switch the earth or power it really dosnāt matter but personally just donāt think its good practice to switch power on L & R, then switch Gnd on Unlock? But it really dosnāt matter.
Take note of the protection diodes ( between S & D ) on each type, you will see the direction is different.
Is this close to what your wanting to integrate?
Would bypass the need for md13 on hydraulic valves I think
@Kaupoi
N type is ok. Connect this way, +12v to 6/2 valve, then to drain (your GND) and mosfet connect to GN4 when on.
Your choice of mosfet is fine, it is fully on at 5 V, and has quite low ohm.
I tried with an old mosfet I had in my boxes with 2,5 ohm full on, but get burning hot already at 1.5 Amp, so changed to IRF3205PBF which has very low ohm. (0.008 ohm). It does not get warm at all running 1.5 Amp. But it cost more.
Until now only 1 hour of test feeding my 6/2 valve.
You need to have some pin choices or some other way to change between dir and pwm2 (cytron or ibt_2)
Edit: I use ibt_2 for my hydraulic valves, and on the old system, a relay for the 6/2 valve.
Edit2: As GoRoNb points out in one of the next posts, normal connection would be switching on the āhigh sideā and using a component like BTS442 sounds like a good idea.
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Yea nothing wrong with N type, but his drawing has Drain to GND witch is not correct Source should be ground.
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Correct me if Iām wrong, but AFAIK nearly all stuff in automotive electric has one pole on battery- and the other one switched, so what you need is a so called āhigh side switchā:
I had a short look and really found (a very good) one in THT technology from Infineon: BTS442 e. g. available here for a good price (if it isnāt a clone).
Connections:
1 0V = battery-
2 valve 6/2 output of Nano
3 battery+
4 do not connect
5 to 6/2 valve
For about 2A, you definitely need no heatsink.
By the way @CommonRail 's suggestion would melt the Nano when driving the optocoupler. I would work with either a small signal N-Ch MOSFET or using the N-ch power MOSFET shown instead of the optocoupler.
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Iām not a electronics engineer haha, you are correct most automotive stuff switchs the high side.
The BTS442 will make one component to switch high side 12v from 5v.
Only dumped the opto in there as thereās plenty on the board anyway (there is a 330ohm resistor on PWM2 I would have thought that would limit current) but small n-ch is better that opto
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A BTS 442 would be good.
I think it would be worth (for safety) to provide an additional 6/2 disconnection with a pressure sensor independently of the Nano. For example, the sensor could supply GND to the BTS 442, opening the circuit (sensor activation) would turn off 6/2
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So I think Iāll go with the BTS442 on the high side then. Thanks everyone.
Do I need a heatsink on BTS442 if itās supplying MD13 and electric steering motor?
Did I get it right this time? 
No additional resistors needed?
Looks ok to me, do you need a protection diode? for when the coil turns off?
Edit: just checked itās built in so thatās not a problem 
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Hi
It seam that the Infineon BTS442 is obsolete at Digikey and Mouser?
Good hint! I checked on the Infineon page and found two non-SMD candidates:
The BTS50055 is available from Mouser and digikey.
Minimal connections:
1, 2, 6, 7 to 6/2-valve
3 to Nano via NPN/N-channel transistor (switched to Battery- = on)
4 Battery+ (supply voltage)
5 not connected here
Seems, the BTS442 is a China clone like the ones used in the China-IBT-2 (the original IBT-2 is really unbreakable)!
This is great. Nice design. I have been looking at modifying your pcb v2 to incorporate ethernet switch on an extended pcb. Iām trying to get rid of a bunch of wiring and the bulk of the ethernet switch. I just got a look at this one of yours, and you have added a can connection.
I could put the ethernet switch into the GPS pcb and put a header pin under your can connection and stack your board onto gps board and have everything without having to make a pcb.
Would you look at my post and let me know if you see any problems with theory ?
Itās under āIntegrated ethernet on pcbā
Thanks
That only adds one connection. I want a switch to connect nano, GPS, and have extra for implement control, all with only one network cable to tablet. I posted a picture on āIntegrated ethernet on pcbā of one that looks like it would work.
Gerber files for KaupoiMOD v4.1 can be found from: https://1drv.ms/u/s!Ao6_PnVNR5RXhONEzuKXPEnrLXZkyQ?e=eobmYy
Can you save as .brd or .sch so I can open it ?
.brd and .sch addedā¦
Iām trying pcb artist. If I get it roughed in, can you clean it up ?
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