GPIO'4'Cars, the way to drive your car with N2!

[zyssai]

This website is wonderful, I didn't know it. The fact to see which way the current takes, I will try to play with it. Perfect, thanks

I will take a look tomorrow with a relay, and see if it works.

[mad_ady]

I remember falstad.com since ~20 years ago, when the simulations were java applets!

[zyssai]

I remember falstad.com since ~20 years ago, when the simulations were java applets!

I've just seen how full it is with math and physics simulators. A little old school but that's the best

[mctom]

I was really angry making that simulation, that interface for adding components is awful.
I prefer SPICE simulators, but those are much harder to use, and harder to share.

One thing you should try is to simulate what would happen if you placed a relay on this output, and why it wouldn't work. Relay coil has some 100 Ohms...

The output voltage is 118 mV. Not quite enough

EDIT: My girlfriend said yesterday she'd like to finally try all that Arduino stuff.
I told her an inspiring story of our French friend who developed an actual product with a little community help.
If you say this is an intuitive and easy to understand representation, I'll use this tool to teach her about amps and volts..

[zyssai]

This website is old you're right but it does the job

I will delay test of relay but will try to add it to your simulation soon.
Happy to know there's some french guys helping with an anecdote

[zyssai]

So here it is
Look at how nicely the widget is, as it is changing regarding the state of the output



I replaced R2 with the same relay as the one used to power N2 with the ATtiny85, it is the exact same schematic.
For the test purpose I just wired a led to N2 1.8v directly to the relay.

I just consider to let user choice to use 12v or some sort of open/close contact.

[mctom]

You can add relay permanently, and provide all three relay contacts, so the user can make anything they want with it.

OR, to save cost and board space and mass, you can make a high side transistor switch instead of a relay.
Related picture below. You'll need a P-type MOSFET for this. Which one? This depends mostly on maximum current you wish to provide with this output.

Don't ever believe the MOSFET current rating in amps. What you want is Ron (On-state resistance) to be low enough so your mosfet doesn't get hot when conducting.
Assuming 100mW maximum loss, and 2A output current, Ron would be..

P = I * I * R
2A * 2A * R < 0.1W
R < 0.1 / 4
R < 0.025, or more commonly 25mOhm.

T1 may be 2N7000 that you are already using.
R1 = 10k will be fine.

[zyssai]

Good advices as always

It's sure relay takes place. The supported current of this smd model is 2A for 12V.
I will study MOSFET solution as soon as I have time to

[zyssai]

I will release, I think before end of May, latest LOS20 from @voodik, including all the necessary changes to make GPIO'4'Cars board working directly out of the box.

[zyssai]

I am actually redesigning an alternative version of the board, for the possibility to attach the N2 and the GPIO'4'Cars board, directly on the back of VU7C screen.
Second reason to this redesign is to remove BT module, because unfortunately I don't find it perfect for every day usage.

As you can see, it will fit like this:



This seems huge, but thickness including VU7C and N2 is around 58mm.
I will design a 3D printed support to fix them together.

[zyssai]

Today I am updating one of the first friend's car where I installed an Odroid.
There was no GPIO'4'Cars board in this one, the wiring was only made with this hand-made box containing some relays:



Notice my Hyundai Tucson with dead gear box synchos. Only 5 years and 130000km.


I have received last revision of the GPIO'4'Cars board, will try to solder components and test it this week

[mctom]

Maybe a dumb question, but is your project open source? I can't find it on github

And sorry about your prematurely broken gearbox. That's a shame new cars are not worth their price.

[zyssai]

For sure, here it is, but I have not updated it since some weeks. I have tons of work and it's hard to prioritize them.

My Laguna have 320000km and gears are working like a charm. Impressive.

[mctom]

Would be nice to link this repository, update it and export PDF schematics for those who don't use the same software. I would be interested in following your changes. If you have a TODO list, it could be included.
I'm watching this repo already, but it's so outdated I forgot about it...

My starlet has done 340k km or so, I bought it 6 years ago with 270k if I remember correctly. I paid €500 for it, because it's slow, small and ugly, and survived a few accidents.
I save €90 for repairs every month, I have amassed €1500 this way. It just won't break down.
There's no way I'm ever going to spend €40k on a new car, especially seeing how they fail after 5 years these days..

[zyssai]

You are right with cars. We bought the new Tucson around 35000€ (approx 35000$) and always mechanical problems.

I found this Laguna 3 for only 1900€ in replacement of my old Laguna 2. A good opportunity as it is full options and powerful.

Please let me know if you want me to send you one board. Greetings are only for you with this project.

Did you check the tutorial post?

Not all is noticed but there is most of needed.

[mctom]

Thanks @zyssai but I use my car so rarely these days I don't think I need Android in it.
I walk to work since I started it last February. I use my car every 2-3 weeks to visit my grandpa and nothing else

[zyssai]

Yes you already told me this a few months ago
But perhaps you could change your mind

I would be interested in following your changes

Can I help you with something?

[mctom]

My car is lucky I upgraded cassette player to a CD player

It would be helpful if you uploaded schematics in PDF on github, at least next time you need help debugging a new problem.
Fingers crossed, this should never happen again.
But keeping files up to date on github will also save you from losing your project if HDD fails.

[zyssai]

Last revision (1.4) is working perfectly as you can see here.
Will make a video soon to demonstrate input and output capabilities.

[zyssai]

Since I have modified GPIO'4'Cars board to fit directly beside VU7C screen, I printed a 3D frame to assemble the whole.
Not found enough time to demonstrate input/output control but will do it soon