My idea was to set up a system to validate a measuring method. And learn a bit about how complicated a simple system can be.
When toggling the 'GPIO voltage supply' I have seen quite great differences of calculated results. So I kept the GPIO stable and looked for possible reasons for the errors.
The resistor values are quite low, so current is 1.3mA. I'd consider this 'low resistor setup'. Have not seen too much noise on the scope. Also I measure some hundred adc values in 0.1ms distance to average out interference from mains.
Using low noise mode for the on board voltage regulator would be an option.
Of course if you measure voltage on a (small) shunt and calculate a resistor which is 6 times larger then a small error in shunt measurement gives 6*error for the measured resistor.
An improved setup could use 4wire connection to the shunt resistor.
When toggling the 'GPIO voltage supply' I have seen quite great differences of calculated results. So I kept the GPIO stable and looked for possible reasons for the errors.
The resistor values are quite low, so current is 1.3mA. I'd consider this 'low resistor setup'. Have not seen too much noise on the scope. Also I measure some hundred adc values in 0.1ms distance to average out interference from mains.
Using low noise mode for the on board voltage regulator would be an option.
Of course if you measure voltage on a (small) shunt and calculate a resistor which is 6 times larger then a small error in shunt measurement gives 6*error for the measured resistor.
An improved setup could use 4wire connection to the shunt resistor.
Statistics: Posted by ghp — Fri May 03, 2024 9:17 pm
