Development USB meter DC

 

Based on the schema of the voltmeter and also the firmware of the microcontroller PIC18F2550 USB made program which helps you calculate the product of electrical energy for a circuit of constant resistance. Because of expensive cost of the purchase of the meter, you can do it yourself. The meter in question intended to measure, and to compare electrical energy recovery engines of various designs, but one of power. In addition, it can be used to measure the energy produced by wind turbines and other different energy sources, DC. The program can read kW*h, W*h, and so on.

The circuit includes a voltage divider acting simultaneously and the resistance (calculated).





Enter in the USB the program marked in red:

 





Blue marked multiplier voltage, which can be obtained before the measurement in accordance with the formula. You can also make a selection according to the multimeter, in other words, by measuring the battery voltage with a multimeter. Then you need to enter a multiplier of the voltage to the USB, it shows on the battery similar to the multimeter value.

The resistance value of the voltage divider, you can choose to skip the small and a large current. In addition, the voltage divider is important when the supply voltage over five volts.

It is important to note that schema in the Proteus, there are differences from the scheme in the gland.









It is possible to increase a counter when you change the firmware of the microcontroller. This microcontroller can measure the current in the circuit and feeding into a USB program. Thus, there is no need to enter the resistance value of the circuit manually.





For the efficient operation of the USB program is important to install Framework 4.0.

USB program is characterized by the ability to process the desired number of connected meters. For these purposes it is necessary to carry out the choice of opening the program and re-select HID-compliant device. Devices meet down in the list.





In USB, the program has the ability to put the noise threshold voltage.





We emphasize that Windows XP program not always works in relation to input and change values of resistance. For these purposes, it is important to clean the event log.

To calculate the DC power, we recommend to use the algorithm USB program:

From USB microcontroller program receives the result measured voltage divided by resistance. Then the measured voltage should be multiplied by the voltage multiplier to obtain the real voltage supplied to the divider on the counter. This voltage is multiplied by current and integrate in time to obtain the value of energy.

 

Source: zeleneet.com