enter image description hereenter image description hereI have opened a Multimeter (Model:DT830D) and I want to take the input that is fed to the LCD display and display it on my PC instead using the serial monitor of the arduino.

But I am confused about the pins which are responsible for sending the measurement values to the LCD display. Because once I find out which pins/circuit wires are responsible for sending for sending the data, I can very easily feed the same to arduino.

  • \$\begingroup\$ Can you post a picture of the opened meter so that people can get an idea of the type of LCD display used? \$\endgroup\$ – crj11 Feb 18 '19 at 14:38
  • \$\begingroup\$ You appear to be talking about the signals between the multimeter's chipset and the LCD driver, those signals usually are "standard logic" signals which you can feed to an Arduino. But if the chipset directly controls the LCD the LCD driver will be inside the chipset. The signals going to the LCD will be very different from logic signals as they control the LCD segments directly and might be more like analog signals. Just googling DT830D meters: OK, a very cheap meter and ICl7106 based, it has the driver on the chip itself. So what you want will be very difficult. \$\endgroup\$ – Bimpelrekkie Feb 18 '19 at 14:46
  • \$\begingroup\$ @crj11 I have updated the pic \$\endgroup\$ – Sachin Kumar Feb 18 '19 at 14:55
  • \$\begingroup\$ @Bimpelrekkie I have updated the pic. Can u check it once and say whether it is possible. \$\endgroup\$ – Sachin Kumar Feb 18 '19 at 14:57
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    \$\begingroup\$ I'm not saying that it is not possible. I am saying that it will be very difficult. Because: no logic signals (do research on how LCDs must be used) and not numbers but segments of the LCD are switched on/off. So you might need extra electronics to properly translate the signals to Arduino levels. You cannot make such electronics without an oscilloscope. You need to write a program to translate segment data back to numbers. \$\endgroup\$ – Bimpelrekkie Feb 18 '19 at 15:00

You should use a multimeter equipped with an isolated serial interface for that purpose. The isolation of the serial interface is important to avoid unwanted grounding of the multimeter circuit.

If you use the multimeter with a connection from the LCD to the PC to measure the power grid voltage (110 or 230 V AC), you may get an electrical shock and destroy the multimeter or the PC or even both.

Using the serial interface for data transfer is easy (been there, done that, but having a good knowledge of asynchronous serial data transmission). Using the LCD signals would be very tricky and difficult.

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  • \$\begingroup\$ could you please give me a bit more detail about your answer. By the tips I am given in the comment section, I definitely understand one thing that I should not try pulling up the values from the LCD signals. Anyways, my main motto is to get the measurement taken by multimeter, and display it in PC. \$\endgroup\$ – Sachin Kumar Feb 18 '19 at 18:11
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    \$\begingroup\$ @SachinKumar The easiest way would be the use of a multimeter already equipped with a PC interface, may be USB or USART. \$\endgroup\$ – Uwe Feb 18 '19 at 18:16
  • \$\begingroup\$ Thanks for the info. But the multimeters with a PC interface facility are very costly (Googled them), and since my budget is not too high, I would prefer taking a normal multimeter and getting the measurements from them, to display on PC. \$\endgroup\$ – Sachin Kumar Feb 18 '19 at 18:27
  • \$\begingroup\$ @SachinKumar May be you find cheaper data loggers with PC interface. \$\endgroup\$ – Uwe Feb 18 '19 at 18:59

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