openXsensor ADS1115: 3 ways to measure current

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Carbo
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Joined: Fri Aug 02, 2013 6:55 pm
Country: Germany
Location: Freinsheim RP

openXsensor ADS1115: 3 ways to measure current

Post by Carbo »

openXsensor allows different ways to measure a current:

- connect current sensor analog out to Arduino analog in (10bit resolution)
- connect current sensor analog out to ADS115 (16bit resolution)
mstrens describes both options in his oXs.config.description.h

A third option is to use a shunt and measure the voltage drop. The resolution of ADS1115 is 16bit, the lowest measuring range is 256mV. If we use only 25 or 10mV voltage drop, it is still a better resolution than with Arduino analog in. Power loss in the shunt is acceptable in my pov. The table shows some examples for 25 and 10mV voltage drop. The shunt is a readymade (SMD) resistor or can be made from constantan wire.

Shunt_calc.png
MessR.jpg
ADS1115 can be configured as 1 or 2 differential inputs and/or up until 4 GND based inputs. Differential is easier to handle, GND based needs a proper GND connection, or will eventually suffer from potential shift. Differential input can handle also bidirectional current, for those who recuperate in flight 8-) or charge solar in flight.

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