Has anyone used the propeller chip for automotive use?
turbosupra
Posts: 1,088
Has anyone used the propeller chip in automotive use, with rpm input?
Does anyone have an example code or circuits for this? Or can post their experiences?
Does anyone have an example code or circuits for this? Or can post their experiences?
Comments
You'll get more information if you give some information about what you're trying to do and perhaps what you've tried so far and your experience level.
I'd recommend a switchmode regulator, good filtering, and preferably isolated ground, even if this forces you to use optocouplers.
The electrical noise, and hazards for electronics in a automotive environment is challenging.
You'll face a noisy electrical supply, alternator and regulator are far from perfect, and the occasional high amp relays turning on and off, sending spikes into the electronics.
Placing the prop to close to any electromagnetic source / sparking, can cause problems if you don't take this into consideration.
Sparking from adjecent relays cause noise on inputs, the reset circuitry is the most noticable, obviously, but you can get the occasional false signal on any input pin.
High temperatur drift on any analogue sensor / circuitry.
Dirt, water and dust, you must ensure proper encapsulation both of circuitry, sensors and connectors.
During cranking of the engine, battery voltage may drop to half when temperature is below 0*Celsius.
RPM
The rpm sensor of different engines varies, but in my experience (old volvo turbo diesels) it supplies the rmp in milivolts via a magnetic pickup on a gear.
my first attemt to interface to this kind of pickup was by amplifying the positive pulses with a transistor and a filter
resulted in a accuracy of +-20 rpms, but periodic spikes so software smoothing was necessary.
So on the current project, where I need to precisely adjust the fuel supply to keep a constant rpm I'll be using a low drop diode bridge, connected to adc
and compensate for the voltagedrop in software.
It might be easier to just use a halleffect with logic output, again this depends on what you're trying to archieve.
This will be an in cabin device. I am a novice at circuitry and inbetween a novice/intermediate with programming
My goal is this
I'd like to have my propeller chip output a specific voltage when my car is off, ignition is on ~ 1.63vdc, then when the car starts (rpm signal) and an outside trigger is received, for it to ramp up to ~1.85vdc, as that trigger releases, to spike to ~2.04vdc and then to fall down to between 1.45vdc and 1.6vdc, and oscillate between that changing once or twice per second.
If I can get this circuit to work, I'd then like the ability to trigger a few low sides based on rpm.
Does this sound feasible? By the way, awesome circuit Erik!
@Havard - I have to admit that you lost me on the spike filtering a little
That doesn't really help, automobile power is equally poor at all points.
Sounds like your trying to do some kind of engine control?· Turbo?· Fuel mix?
Fwiw, JayCar sells a lot of that stuff at good prices.
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I've looked through Jcar, they don't have anything close to what I need as far as the voltage stuff, so I guess I'll have to build my own [noparse]:)[/noparse]
It won't adjust fuel or boost, but is for a small test project I'm trying to do.
www.auto-facts.org/autorepairmanuals.html
www.alldatadiy.com/
-dan
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Arguing with myself--sometimes me, myself, and I don't always agree.
Of the things I've lost, I miss my mind the most.
http://www.parallax.com/tabid/774/Default.aspx
http://www.parallax.com/Portals/0/Resources/Custapps/Industrial/custapp/Tach05-L.jpg
I prefer using a npn and a pullup on the inputs, as a good old bipolar transistor is more resistant to high voltage spikes than cmos inputs, plus you can tailor the threshold with your resistors to match the voltage levels.
Also, it is highly unlikely that many cars actually have a tach signal coming up to the obdII port. You can use a fuel injector wire also, but there would be no tach signal when decelerating.
If I understand this correctly, 11v to 14v going into the transient voltage suppressor, then into the 5v reg and then into the propeller chip? Do you feed it into the vss pin? I have a Toyota very similar to his, although I was planning on using the ignition signal for coil #1 coming out of the ecu, and not an obd2 port even though I thought obd2 was a standard, so that all cars had the same data coming in and out, in the same format?
Do you use the npn and resistor to feed specific voltage values into one of the i/o's?
It wasn't meant to stop you from having fun!
Every line that is going to or from your board will work like an antenna picking up any noise. Every input should have a R then a small C and fast clamping diodes to Vcc and Vss. Output should at least have an R.
Don't be astonished if your circuit works on the kitchen table, but not in the car.
Nick
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Never use force, just go for a bigger hammer!
The DIY Digital-Readout for mills, lathes etc.:
YADRO
U7 is a schmitt trigger nc7s14, I think. I am using an opto for the fuel injector which works well.
They made it $15 for 2 days now, haha
I actually downloaded all the pdf files I could from that, when I had my 2 day subscription, in case anyone wants to see the documents.
I also just bought the full factory service manuals yesterday [noparse]:)[/noparse]
How much is it for you breadboard + all of the components necessary to build it out of curiosity?
If not, I can build a schmitt trigger out of a 555 timer circuit, correct? And use that to buffer the rpm signal input from the trigger wire that goes to coil pack #1?
Connect two faster (1N4148) diodes to Vcc and Vss behind the R.
Behind the phone jack, I would pace an R (about 100R) to make a filter. And an extra 100nF parallel to C1.
Or a chocke coil.
As drawn, this certainly won't work in a car.
Nick
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Never use force, just go for a bigger hammer!
The DIY Digital-Readout for mills, lathes etc.:
YADRO
And the phone jack are you referring to the LM2940 voltage regulator or the terminal block?
Sorry, I should have written "power jack".
Yes, the Prop works with 3.3 V.
Nick
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Never use force, just go for a bigger hammer!
The DIY Digital-Readout for mills, lathes etc.:
YADRO