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USB Voltmeter

USB voltmeter is a small module to measure DC voltage.The USB Voltmeter sends measured data to PC via USB and a computer displays the data on a monitor. The voltmeter is supplied via USB cable and no external power supply is needed. This web page presents four types of USB voltmeters. They differ from each with measured range, accuracy and resolution.
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USB Voltmeter features :

  • 16-bit A/D converter used
  • differential input [ measures plus and minus voltage ]
  • driver installation is not necessary - it's plug & play device
  • works as a HID device [uses unique VID / PID number]
  • all voltmeters have excellent linearity and very low error.
  • we support Windws XP, Win 7, Vista and Linux
  • API and source code for Windows and Linux
  • powered from the USB cable [ no external power supply ]
  • this type is not galvanically isolated from PC
  • logging data to a .csv file
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USB Voltmeter hardware

USB voltmeter consist of A/D converter and a microprocessor. They are connected via SPI bus. This type is not galvanically isolated from the PC. The microprocessor sends measured data through USB to the PC. USB input USB voltmeters is voltage divider.He reduces the input voltage to the desired range, then this voltage is processed in the A/D converter. A/D converter is the type LTC2482, which is a 16-bit A/D converter. It includes an input buffer and is characterized by high accuracy.

Technical parameters (T1 - T4)

  • Size : 51 x 49 mm
  • input impedance : 1MOhm
  • Measured speed : 6 times/sec
  • USB connector : type B
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Bottom site
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Schematic

USB Voltmeter - 4 types

USB voltmeter has 4 versions that differ from each other only with the measurement range.

Type Range Resolution
T1 +/- 50 V 0.1 V
T2 +/- 50 V 0.001 V
T3 +/- 5 V 0.0001 V
T4 +/- 0.2 V 0.00001 V
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USB Voltmeter software

USB Voltmeter is supplied with software USBMeasure.exe. It is standard Windows aplication for communication with the USB Voltmeter. All the necessary files are in the installation package and software installation is easy.

API

We offer easy API for creation of custom applications. API contains all function to ensure measurement and data transfering to the PC via USB. API contains only several function and usage is very easy. Developer only call these functions and make their own graphical interface (GUI).

The API is implemented as a COM component (USBMeasure.dll). This component can be used in all known programming languages. It was tested with C#, C++, Visusal basic, Delphi and Javascript.

Linux

Linux also supported. The source code for Linux come from our users. We have not tested them but we assume that they work properly.

USB Voltmeter - HID device

USB voltmeters are HID devices (Human Interface Device). These devices use USB drivers already installed by default in Windows. It's the same type of communication as a PC communicates with the USB mouse or USB keyboard.

This applies to all versions of Windows - from windows XP above. USB voltmeters have their own unique VID & PID numbers, so there is no possibility of collision between other USB devices.

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USBMeasure.exe software
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API & simple aplication

Simple example how to use API. You need to use only 3 functions : USBMOpen(); USBMGetData(); USBMClose();
using System; using System.Threading;
using System.Collections.Generic;  using System.Text;
using USBMeasure;   // add reference to USBMeasure.dll

namespace USB1
{
    class Program
    {
        static void Main(string[] args)
        {
            CUSBMeasureMain usb = new CUSBMeasureMain();
            usb.USBMOpen();
            while (true)
            {
                usb.USBMGetData();
                if (usb.Result == 0)
                    Console.WriteLine("Voltage : " + usb.UnitData.ToString("#00.000") + " Volt");
                Thread.Sleep(400);
            }
            usb.USBMClose();
        }
    }
}
 
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Download software

USB voltmeter software ; [ Size : 25 kB ] :temp-thumb
USB voltmeter API ( USBMeasure.dll ) ; [ Size : 719 kB ] :temp-thumb
Source code for Windows ; [ Size : 124 kB ] : temp-thumb
Source code for Linux ; [ Size : 56 kB ] :temp-thumb
This software is only for USB voltmeters Type 1 - Type 4. Source code was tested on Visual Studio 2010.

Software for Linux is provided by Mr. Frank Lassowski. Many thanks for that. This software applies the GNU General Public License.
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Data logging

USBMeasure.exe software allows you to store measurement data to .csv file. CSV file can be read in Microsoft Excel and other programs. For example csv file is here.

Accuracy

USB voltmeter has a simple design but achieves very high accuracy. She is almost like precision instruments. The video shows testing of USB voltmeter Type 3. The same accuracy also have other types.
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