2019-07-14, 12:15 PM
(2019-07-13, 04:14 PM)rmvdmrl Wrote: Hi Skeyedoc,
TMHO. You should connect a 1k resistor from the IBT2 IS to ground that should give a 8.5 ratio from current to Vis (BTS7960 datasheet). So with a current of 15 Amps there should be 1,764 volt (15/8,5) on that resistor (with a max of 7 volt in current limit mode but standard that should be with 43 Amps/8,5=5.05 Volt). Off course you want the Arduino to measure and give the right current. Just for an example According to ohm's law a shunt of 0.05Ohm (one of the options with the Arduino/Pypilot) should give a voltage of 0.75 volt at 15 Amps (that is also what the code in motor.ino measures (low current 20 Amps Max) (1024/1,1(refvolt)=931 x 0,75V = 698,2 x 275 /128 =1500) therefore you could (and should because of the possible 7 volt) use a voltage divider of 100Kohm and 74Kohm that will result in a voltage of 1,764V/174KOhm X 74Kohm=0,7502 volt. So Your measured current should be reasonably right. I hope this will put you in the right direction and off course I can’t give any guaranties as most off the time I have no idea what I’m thinking or doing.
Greetings Rob
These notes are extremely helpful! I'd had no understanding of how the measured current worked. I'll try these values soon.
Thank you!