2020-11-28, 11:59 AM
(2020-11-27, 09:13 PM)PaddyB Wrote:(2020-11-27, 08:54 PM)affinite Wrote: Holger and Paddy
Thanks for the advice
I only want the device to measure Current (In and Out) as I already have an ADS1115 measuring voltage.
I've been experimenting with the INA219 (with the onboard shunt removed) this afternoon.
I've also tried amplifying the shunt voltage using an AD620 Millivolt Amplifier which is adjusted for enough gain to give 3.3v (at Full Scale - 100A) and then measured in differential mode by an ADS1115. That seems to work well so I'll compare with the INA219 over the next few days
Regards
Steve
Don't think you need to amplify the voltage, the INA already has a high quality amp built in so can measure down to micro volts. The gains are adjustable, or should be when instantiating an instance of the library >
GAIN_1_40MV = const(0) # Maximum shunt voltage 40mV
GAIN_2_80MV = const(1) # Maximum shunt voltage 80mV
GAIN_4_160MV = const(2) # Maximum shunt voltage 160mV
GAIN_8_320MV = const(3) # Maximum shunt voltage 320mV
GAIN_AUTO = const(-1) # Determine gain automatically
Thanks
I was only amplifying the voltage when measuring shunt voltage drop with the ADS1115
With the INA219 I'm using ESPEASY where there doesn't seem to be an option to adjust the gain.
I'll look again this afternoon.