Hey, I am a Mechanical Engineer major at Cal State Fullerton and was put in charge of a little task which has proven to be more than my mechanical brain can handle.
I was given a "Luster Leaf 1845 Rapitest Digital Soil pH Meter", and I have to ditch the LED screen provided and instead read the information using an Arduino Uno board.
Does anyone have any thoughts on where I should begin, if this is possible, or any material that I can read up on to make this task go by faster. Thank you
Also, I can write basic code in Arduino and Labview.
A pH meter is really just a millivolt meter reading the millivolts from the electrochemical cell at the end of the probe. You could either try to hack the display and intercept what was intended for the display, or you can go back a little further and find where it is reading the millivolts and hack that so that you can take your own reading.
This is the manufacturers page : Luster Leaf Gardening Products - Outdoor Meters & Thermometers
This is the manual for it : http://www.lusterleaf.com/img/instruction/1845_instruction.pdf
Open it and make a photo of it, perhaps we can tell how hard it will be.
Perhaps a common opamp is used, and the signal after the opamp can be used.
A battery operated PH meter is on its own. An Arduino has the GND often connected to a computer, and that makes it harder to read the PH value.
If you can read the data with an Arduino running on a battery, you avoid many troubles.
There are sets for Arduino with a PH sensor : pH Sensor Kit - SEN-10972 - SparkFun Electronics
Sorry for the wait, but here are the pics.
A single chip under the display, that's all ? You are in so much trouble.
All I can say is what Delta_G already wrote in Reply #1.
Capturing the signals to the display, or the millivolts from the sensor would be a lot easier if you had the schematic or the part number of the display and chip.
To capture the data to the display is not easy, it is something for advanced tweakers/hackers.