It's not too difficult to decode multiplexed signal that goes to LCD.
I have done it with kitchen scale + HC4050 buffer IC + arduino.
My setup:
I was planning to write an article on this topic but never got to it. I'll try to be short.
It's helpful understand how multiplexing works. I have found this document (and many others, just google lcd multiplexing):
http://www.nxp.com/documents/data_sheet/PCF8576C.pdfFirst you need to examine pins to find out which are backplane pins and which are segments.
Then use the oscilloscope to record the timings of the signals.
I connected lcd pins to arduino like this:
In arduino code I set rising interrupt on backplane 0.
After that I waited, read signals, waited, read signals etc...
I was reading 8 signals at 4 different times to get status of 32 segments.
But to figure out which of the 32 bits is responsible for each part of segmented characters I made setup like this:
Connect each backplane and each segment pin to 3.3V square wave and one segment will turn on.
I hope this helps.