DIY AutoSteer with AgOpenGPS - Page 188 - The Combine Forum
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post #1871 of 1878 (permalink) Old 07-06-2019, 06:19 PM
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Originally Posted by Andreas Ortner View Post
Brian, the acutal agopen repro contains only one sketch which runs with ads.

i think thats not so good because the mainly users are driving without it..

Can you be more specific on which repo you are referring to and also what the problem is?
He means the Arduino sketches in your main AoG repo only have the differential analog code.

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post #1872 of 1878 (permalink) Old 07-06-2019, 09:44 PM Thread Starter
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He means the Arduino sketches in your main AoG repo only have the differential analog code.

Well can't be that. Only the comment says differential - I suppose that is good to correct. Or do you mean using A0 perhaps?

Code:
    

steeringPosition = ads.readADC_SingleEnded(0);    //ADS1115 Differential Mode                            

steeringPosition = (steeringPosition >> 3); //bit shift by 3  0 to 3320 is 0 to 5v  

                    

steeringPosition = (steeringPosition - steeringPositionZero - (XeRoll * Kd/10 ) );   //read the steering position sensor 

if (SteeringRightIsNotPositive) steeringPosition *= -1.0;    //steering position and steer angle


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post #1873 of 1878 (permalink) Old 07-06-2019, 09:51 PM
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Yeah, he means it only has the ADS, it needs A0.
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post #1874 of 1878 (permalink) Old 07-07-2019, 12:48 AM
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Originally Posted by m_elias View Post
Yeah, he means it only has the ADS, it needs A0.
Yes, most of the user do not use the ads. So there should be an option a0 or ads .

Like autosteer switch by weder.

or you just insert weders sketch .. (autosteer_switch)

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Last edited by Andreas Ortner; 07-07-2019 at 10:00 AM.
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post #1875 of 1878 (permalink) Old 07-08-2019, 12:49 AM Thread Starter
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Yes, most of the user do not use the ads. So there should be an option a0 or ads .

Like autosteer switch by weder.

or you just insert weders sketch .. (autosteer_switch)

My thoughts are using 10 bits would be the worst mistake building autosteer.
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post #1876 of 1878 (permalink) Old Yesterday, 03:15 PM
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So Brian, you think using the ADS1115 is a hudge improvement over just connecting the WAS to the Arduino?
Not using the ADS is not done if you want a accurate functioning system, is that what you mean?
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post #1877 of 1878 (permalink) Old Today, 02:34 AM Thread Starter
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So Brian, you think using the ADS1115 is a hudge improvement over just connecting the WAS to the Arduino?
Not using the ADS is not done if you want a accurate functioning system, is that what you mean?

Well the Arduino a/d convertor is only 10 bits. that means you get 1024 counts across the total movement of the sweep of the Wheel Angle Sensor. Theoretically that is about 20 counts per degree or about .1 degrees per bit (100 degrees turn over the counts available). Practically however you end up using around 3 volts and with jitter of the a/d convertor its really only 9 bits or 512 counts which works out to around .2 or even .3 degrees of actual resolution - add in the problem of some delay and positioning and the thing wiggles back and forth a half a degree. Add all the digital noise within the Arduino, its very crappy drifty reference voltage and its even worse. Not the best at all - in fact terrible.



The ADS is 15 bits (yes its a 16 bit chip capable but we are only using a single polarity) so we start with 32,768 counts losing a bit with jitter that's 16,000 ish counts or around .006 degrees per bit. We take and seriously divide that and bitshift it 3 positions which becomes 5000. Now the gain of the ADS is 2/3 of the input signal so at worst case its around 3000 counts - or .03 degrees. So we end up with a positioning system around 20 to 30 times better that is rock solid and accurate.



That's why I can't recommend at all using the arduino a/d convertor, and if you want good steering just use the ADS.
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post #1878 of 1878 (permalink) Old Today, 02:56 AM
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Thank you Brian, you convinced me, will order one right away,


Simon
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