I would like to hack a digital scale by wiring to the 16 pin input to the LCD screen on the scale and reading the values with a date time stamp to a log.
I looked into designing a load cell and then building converters etc but it is much simpler and cheaper to buy a scale than build it by components.
I want to keep the scales LCD readout in place on the scale but output the readings at the same time.
The circuitry for the load cell conversion to LCD output are covered in epoxy but I can get access to the LCD output tracks on the board and could solder to these.
Any ideas welcome.
Study Arduino code and connections to a similar LCD display - it should give you some idea of what to expect.
If you can find the exact LCD used in your scale and get a datasheet for it things will be much easier.
If the LCD includes a processor so that data is sent to it occasionally you will probably have a harder job.
...R
Usually, digital scales use a passive LCD panel, and it's not trivial to piggyback it and read out the signals, since it's more than just high/low.
http://awawa.hariko.com/avr_lcd_drive_en.html
I would never recomment trying to piggyback a multiplexed LCD and trying to read out the signals, but one, specially crazy poster did just that (He could just have connected the analog signal to Arduino's AD-converter ...)
http://forum.arduino.cc/index.php?topic=180333.30
What you need is this: http://www.ebay.com/itm/171166792321
// Per.
Robin2 , Zapro, thanks for the feedback.
Screen is non descript so dont have a reference to lookup. Processor is behind epoxy so cant see much there either. Probably too hard to go this way. I am really after the loadcell output anyway.
After looking at how it was done that was some hack! Much easier to buy the AD converter and read directly from the load cell. I ordered the ad converter and will let you know how I go. Heres a couple of pictures of the board and load cell for reference.
Gezzanet, I am curious. What did you finally do to hack he scale. hacked into LCD input or re-did the a/d conversion? I am trying to do similar- hence your input will be appreciated.