How to calibrate the Voltage Port
For board series RPICT7V1 RICT4V3 RPICT3V1 and EmonWRT the voltage should be calibrated against the AC/AC adaptor used. We will explain how to calculate this value here.
- Any ac voltage measuring device (multimeter, scope).
- The board to test must be operational.
Setup in configuration an approximate value for VCAL. You might just use the default provided to start with. We will use VCAL = 545.0 in our example.
This can be anything but should be relatively close to the expected final value.
Connect the ac/ac adaptor to the board to be tested and note the reading of the measured voltage given by the RPICT. Let's say in our case Vmes = 269.5
Use the multimeter to read the real voltage value. In our case Vreal = 245.6
Calculate the new VCAL as such
newVCAL = VCAL*Vreal/Vmes
For us here this is newVCAL = 525*245.6/269.5 = 478.44
Enter the newVCAL value in the configuration.