ATmega32 10A 2-channel current meter with LCD display

2 channel 10 amp measuring circuit ATmega32 is based on the large lcd used for the display 128×64 SED1330 can measure 2 channels 10 amps automatically It can detect AC DC This project is a 2 channel ammeter. The channels are completely isolated up to 2000 volts. I’m sure you don’t need such isolation, but it may be necessary to measure the charging current for the input of 110V AC or the output of something like 12V DC. That is, it provides automatic detection for AC or DC current.

The main part of this project is the cold DIP 14 current sensor ZMC10, which supports up to 10 A. The current is measured by the hall effect sensor inside. I used a graphic LCD to show very large numbers of current read and maximum peek, DC or AC.

Ok now, this was supposed to be simple but I had to overcome a lot of problems while making this project. First of all, ZMC10’s datasheet has 2 big pages!

How can an IC like this have 2 pages of documentation when the LED datasheet has more than 15 pages? Not having the proper documentation was the biggest challenge for me. I had to calibrate at first to use it from 0 to 10 amps, the slope is not linear. Software, Y2 – Y1 / X2 – X1 | B = Y – M * X | X = Y – B/M | Y = M * X + B.

After encountering another problem, any piece of metal more than 2 inches will make the reading completely wrong. For example, if your charge is 5 A, moving a 2-inch screwdriver of the ZMC10 will give you something like 1A or less.

The other problem I’m running into is that if the 2 sensors are closed to each other the current will mix and give you a false reading. I had to rebuild another PCB to separate each channel.

Also at 0 A the sensor will not give you zero, you have to calculate the offset from one part to the next as the values are not the same. Finally, if the current flows from A to B or from B to A, not all values, slopes and offset are the same. I think this poses enough problems for a simple ammeter.

The MCU has two jobs: measure (calculate) the value from the analog card and display that value. I drove the LCD in graphics mode. I wrote character generator for 1x, 2x and 4x fonts for other functions like line drawing, square, clear screen and more. In addition, the MCU board has the power supply for itself and the analog part.

Features

2 Channels
Small from 0 to 10amp
0.1 amp small Resolution
2000 volt isolation between each channel
Automatic AD/DC detection
Very large LCD and character

Source: http://www.microsyl.com/ampmeter/ampmeter.html