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0-5v output for MAF simulation


boostDR
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Only our Kurofune ECU has analog outputs designed for piggyback type sensor simulations.

If you have one of our other ECU's then you will need to use a GP PWM, and add a basic external circuit with a 5V pullup and a R-C filter to smooth the PWM signal down into an analog looking signal.  Remind me in a day or two when Im back at work I will draw a quick diagram with some recommended values & settings.

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1 minute ago, boostDR said:

Done. Will post up the frequency vs voltage once I do some testing.

The frequency should be fixed at 1000Hz, as above.  Duty cycle is what you vary.  It should work out pretty close to: 0%=0V, 50%=2.5V, 100%=5V.

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I have it set up as GP PMW and 1000hz constant. 

Duty: 100% is 3.3v and 0% is 6.8v 

The PWM output goes to ground at 100% and sits at about 7v at 0%. Wondering if I’m doing something wrong. Can seem to get the required scaling. 

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Ok, modified the cct. Works as expected now, thankyou.  

15 % duty at 1kHz is 5.1v 

84.5% is 0.05v 

response time is ok. You can see a slight ripple at the second decimal point. I might try 4kHz on the weekend and see how it goes. 

 

Matt

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  • 1 year later...

Hi Guys,

I was hoping to use this circuit to run a Geartronics gear display as I am using the 0-5v signal from the barrel sensor as an input for the Fury ECU for closed loop shifting. I realise an easier way would be to simply splice into the barrel sensor signal for both the ECU and the display, however I have been told by the distributor of the Geartronics system that this will not work as it will give inconsistent results (not sure why this would be the case).

The current problem I can foresee is that the Fury does not allow me to output a PWM signal with a frequency greater than 300hz.

Can anyone confirm the best way around this?

Thanks.

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1 hour ago, Brad Burnett said:

Aux 5 to 8 can not be Pulse Width Modulated (PWM) above 300Hz. Note that PWM frequencies above 300 Hz may be required to drive a tachometer for a V8 above 4500 RPM.

Thanks Brad,

I'll switch some functions about so I can use aux 1-4

 

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  • 1 year later...

Hi,

been trying to use this method to drive some stock analogue temp/oil pressure gauges in an old commodore. 
 

I’ve been trying for a couple days and cannot for the life of me get the results mentioned above. 
hooked up exactly as above all I can get out of the aux output is a constant 6.5v when pull-up hooked to 5v or constant 12v when pull-up is to 12v. 
 

changing frequency and duty cycle does nothing. 
 

any idea ideas. I even hooked up on the bench with no gauge and same results. The pwm output doesn’t seem to do anything. 
 

On 4/12/2018 at 9:04 PM, Adamw said:

Crap I just noticed a mistake in my drawing sorry.  The pull-up should have been on the other side of the 1K.

DeuDb26.png

Hooked up as per @Adamw 

ecu aux is aux 1 on a thunder ecu, set to gp pwm tried constant frequency of 10-4000 with no change in output voltage. I have the cap going polarity to ground. 

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3 hours ago, Adamw said:

That suggests the aux is working then.  Test(ON) is the same as having 100%DC in your GP PWM table.  Have you got the activation conditions set up and the aux status runtime shows "On"?

doh!!

I had switch condition set to ignition and somehow entered 2 instead of 1 in so it wasn’t activated.  
I had checked the runtime value earlier and it was on so I tripped myself up along the way somehow. 

Working now, thanks heaps for your help @Adamw 

FYI, I didn’t need the RC filter to work on this early commodore. Works fine without it but wouldn’t work with it at all, which I find a little confusing.  I assume I need to remove the pull-up and just run the r-c combo but it’s working good so won’t bother. 
 

Thanks again. 

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