# Comments: INA169 Breakout Board Hookup Guide

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• Puzzled. I just hooked this up. I’ve got a small solar paned (20v/300ma max homemade). I use a 1 ohm for RS to fit the range I’m looking for. I get 0.00A return. I changed the line of code (const int RS=10) to RS=1 to reflect the resistor rating (I removed the 10 ohm RS resistor). I checked the panel and it’s delivering 50 mA un hooked. When hooked, the RS shows a .05 voltage drop, which of course fits ohm’s law of 1 ohm x .05 amp= .05 v. The hookup is: ground breakout to ground Arduino; vcc breakout to 5v arduino; positive of the panel to Vin of the breakout; negative of the panel to Vout of the breakout; Vout breakout to A0 arduino.

• From what I understand of your hookup, you have the panel connected to Vin and Vout of the INA169 breakout board. It should be like this:

• Breakout GND – Arduino GND
• Breakout VCC – Arduino 5V
• Breakout Vin+ – Solar panel positive
• Breakout Vin- – Load positive (e.g. a power resistor connected to ground)
• Breakout Vout – Arduino A0
• Solar panel negative – GND

Let me know if that doesn’t work.

• Would load negative also go to ground, as in the common grand with arduino and breakout ground? I’ve got a 5w 1 ohm resistor I could use.

• Thanks. It seems to work. I’m sensing from a homemade charge controller that goes to a deep cycle battery to reference the current. When I put Breakout Vin on one of the legs of a resistor on the charge controller, I get a reading, though it’s about 20 ma lower than the current that’s actually making it to the battery. Is this a pretty standard loss that I need to calibrate and write into the sketch?

• Glad to hear it’s working. 20mA seems a bit high. Do you have a multimeter that can measure current? Try this:

Solar + -> multimeter + -> multimeter - -> breakout Vin+ -> breakout Vin- -> load resistor + -> load resistor - -> solar -

Then, measure the current on the multimeter and compare it to the current calculated by measuring Vout on the breakout.

• I did by measuring the current on the output leads that would be going to the batter (not while they’re on the battery, of course).. I’ll try it the way you suggest soon. It’s getting dark here right now, so I’ll pick this back up in a few days after Christmas and let you know. Thanks for all the feedback so far!

• It can be connected to the common ground (with the Arduino and breakout), but it doesn’t have to be. For example, you could have the circuit:

Solar panel positive -> VIN+ -> VIN- -> power resistor positive -> power resistor negative -> solar panel negative

• Hi Sparkfun/Everyone,

I am trying to use the INA169 board with an arduino and a 1 milliohm shunt resistor. The shunt is a 100A, 1 milliohm resistor, so a 100mv drop @ 100A. To measure this with the Arduino I bought this sensor and removed both RS and RL resistors. I use the shunt as RS and a 51k resistor as Rl, To get a 5V Vout, using the equation I get 5.1V = (51000x100x.001)/1000.

Right now I have the Arduino GND connected to INA169 GND and the power rail GND. The Arduino has 5V to the sensor. The vout to a0. The vin- goes on the load side of the shunt and vin+ goes on the source side. I thought this would have worked? But for some reason it always reads zero.

Any help would be appreciated. :)

Peter

• Do you have access to a multimeter? Can you measure the voltage on Vout without the Arduino? Your equation seems right, and it should be outputting 5.1V.

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