Finally I decided to release all design files!
Do you want to have a look how it works internally?
...build your own version of it?
...or extend the functionality?

Now It's your turn!

First of all, here the most important parts of this post:

Sourcecode: lcr_meter_sourcecode_15-03-2014.zip
Schematic & Layout: lcr_meter_schematic_layout_eagle_5_9_15-03-2014.zip

License

I spend a lot of my limited time to develop this. I really enjoy if somebody is using, improving it or usings parts to create something completely different.
Do whatever you like with it, as long, as the whole project or parts of it are used for non-commercial purposes.
Please provide credits.

For commercial use, even if only parts of this is used in indirect or direct form, please contact me.

About the code

The code was developed with IAR for MSP430. It should compile with other toolchains as well, with minimal changes. I did not test it myself yet.
The code is structured in different submodules, e.g. pga.h/c to controll the PGA, dac.h/.c to control the DAC, lcd.h/c contains the LCD code, and so on...

Behaviour of the device

After inserting the battery, the device will start a calibration cycle.
This calibration will improve the common mode rejection ratio of the differential amplifier, calibrate the gain factors of the PGA, ...
Follow the instructions shown on screen.
BTW: The calibration constants of my device are the default values. Have a look at main.c for comparison with the constants you will get.

Button

The button has 2 purposes:
1.) turn the device on and off. The device can be turned off by pressing the button long, until the screen turns off.
The devices uses the power saving modes of the MSP430 do decrease the current consumption to a minimum. The power supply of LCD and analog components is also turned off, when the device is turned off.
2.) Select between the different measurement frequencies.

Formulas

I've been asked pretty often, how the calculation of the impedance works. Here a PDF showing the formulas, and transformations to get them:
Basic_formulas_for_LCR_measurement.pdf

Disclaimer

Don't blame me, if this burns down your hose, hurts your cat, burn your fingers while soldering, ...
Use it at your own risk :-)