How to calibrate the Voltage Port: Difference between revisions

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For board series RPICT7V1, RICT4V3, RPICT3V1 EmonWRT the voltage should be calibrated against the AC/AC adaptor used. We will explain how to calculate this value here.
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.


==Equipment needed==
==Equipment needed==
* Any ac voltage measuring device (multimeter, scope).
* Any ac voltage measuring device (multimeter, scope).
* AVR programmer
* Raspberrypi
* The board to test must be operational.
* The board to test must be operational.


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===Step 1===
===Step 1===
Upload the sketch where VCAL is a know value. We will use VCAL = 525 in our example.
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.
This can be anything but should be relatively close to the expected final value.


===Step 2===
===Step 2===
Connect the AC/ac adaptor to the board to be tested and note athe reading of the measured voltage. Let's say in our case Vmes =  269.5
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


===Step 3===
===Step 3===
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  newVCAL = VCAL*Vreal/Vmes
  newVCAL = VCAL*Vreal/Vmes


For us here this is newVCAL = 525*245.6/269.5 = 478.44
For us here this is newVCAL = 545*245.6/269.5 = 496.67


===Step 5===
===Step 5===
Enter the newVCAL value in the sketch and upload to the MCU.
Enter the newVCAL value in the configuration.

Latest revision as of 10:12, 19 November 2019

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.

Equipment needed

  • Any ac voltage measuring device (multimeter, scope).
  • Raspberrypi
  • The board to test must be operational.

Steps

Step 1

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.

Step 2

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

Step 3

Use the multimeter to read the real voltage value. In our case Vreal = 245.6

Step 4

Calculate the new VCAL as such 

newVCAL = VCAL*Vreal/Vmes

For us here this is newVCAL = 545*245.6/269.5 = 496.67

Step 5

Enter the newVCAL value in the configuration.

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